<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:5e4747c7-5c22-487e-b482-def2c8d2904f,g:835eda77-b821-4a62-aa99-db9974a51909-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="nrg-20231231.xsd#CONSOLIDATEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_2f87d2b8-2a25-480f-8db7-5b8c427d22d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_d462aa8a-0a70-424a-837f-2f689f660f51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_2f87d2b8-2a25-480f-8db7-5b8c427d22d9" xlink:to="loc_us-gaap_StatementTable_d462aa8a-0a70-424a-837f-2f689f660f51" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d81ef474-8d5a-41f9-bbe6-6fe00b1f383d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_d462aa8a-0a70-424a-837f-2f689f660f51" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d81ef474-8d5a-41f9-bbe6-6fe00b1f383d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d81ef474-8d5a-41f9-bbe6-6fe00b1f383d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d81ef474-8d5a-41f9-bbe6-6fe00b1f383d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d81ef474-8d5a-41f9-bbe6-6fe00b1f383d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_dae6c335-dc30-413c-8ab6-711933b0f9d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_d81ef474-8d5a-41f9-bbe6-6fe00b1f383d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_dae6c335-dc30-413c-8ab6-711933b0f9d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_e4ed2b7a-5afe-4433-8320-0bda7e55901a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_dae6c335-dc30-413c-8ab6-711933b0f9d4" xlink:to="loc_us-gaap_CustomerRelationshipsMember_e4ed2b7a-5afe-4433-8320-0bda7e55901a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_7b57aff8-296f-4b32-b369-ff613fb6a268" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_dae6c335-dc30-413c-8ab6-711933b0f9d4" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_7b57aff8-296f-4b32-b369-ff613fb6a268" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_aa3f9053-4dc7-40e9-9ea5-d653635d88b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2f87d2b8-2a25-480f-8db7-5b8c427d22d9" xlink:to="loc_us-gaap_AssetsAbstract_aa3f9053-4dc7-40e9-9ea5-d653635d88b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_aa3f9053-4dc7-40e9-9ea5-d653635d88b5" xlink:to="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_91f81ea1-2823-4ae6-ab2d-5cefe9f0a9d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_91f81ea1-2823-4ae6-ab2d-5cefe9f0a9d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FundsDepositedByCounterparties_6161c323-4351-4ae6-822b-c6d457f89e35" xlink:href="nrg-20231231.xsd#nrg_FundsDepositedByCounterparties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_nrg_FundsDepositedByCounterparties_6161c323-4351-4ae6-822b-c6d457f89e35" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_4519a27c-8188-4d5d-8c92-d4716a77bcaf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_4519a27c-8188-4d5d-8c92-d4716a77bcaf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_a8c29801-89b0-42a4-b002-ba1bf5bb16d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_a8c29801-89b0-42a4-b002-ba1bf5bb16d0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_e590a4bb-0919-4b57-b9cf-853487ff58c8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_us-gaap_InventoryNet_e590a4bb-0919-4b57-b9cf-853487ff58c8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedges_7e23a87a-59d8-4105-ad69-a91a0820a744" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsAndHedges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedges_7e23a87a-59d8-4105-ad69-a91a0820a744" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeLiabilityNotSubjectToMasterNettingArrangementCollateralRightToReclaimCashNotOffset_c67fa2b1-9603-43c5-b7bf-b334e46210f6" xlink:href="nrg-20231231.xsd#nrg_DerivativeLiabilityNotSubjectToMasterNettingArrangementCollateralRightToReclaimCashNotOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_nrg_DerivativeLiabilityNotSubjectToMasterNettingArrangementCollateralRightToReclaimCashNotOffset_c67fa2b1-9603-43c5-b7bf-b334e46210f6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_1ce2928a-b7d0-4fca-89c2-3a50227ba7c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_1ce2928a-b7d0-4fca-89c2-3a50227ba7c6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_17a15f02-2ab3-47d4-9287-909a459dbbbb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_dfb9bfda-dca0-40e9-8100-c69040716b73" xlink:to="loc_us-gaap_AssetsCurrent_17a15f02-2ab3-47d4-9287-909a459dbbbb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_e1bcad12-8f1f-4781-8d87-c6a70db70646" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_aa3f9053-4dc7-40e9-9ea5-d653635d88b5" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_e1bcad12-8f1f-4781-8d87-c6a70db70646" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_aa3f9053-4dc7-40e9-9ea5-d653635d88b5" xlink:to="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_5683b3f6-b3e8-44fa-b7d4-f3f14921ec6b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_EquityMethodInvestments_5683b3f6-b3e8-44fa-b7d4-f3f14921ec6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_fe9ff5eb-408f-495c-b3e2-53ad54963830" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_fe9ff5eb-408f-495c-b3e2-53ad54963830" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_af1841fc-eece-4586-8394-86142b0ab151" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_Goodwill_af1841fc-eece-4586-8394-86142b0ab151" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_a3d5bc54-4af0-4afb-8713-c1a3c41e5352" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_a3d5bc54-4af0-4afb-8713-c1a3c41e5352" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_ffdc2237-19c5-4e5c-839d-2fecda0486f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_ffdc2237-19c5-4e5c-839d-2fecda0486f4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgesNoncurrent_5ea7341d-b61b-46fa-b865-19f17da5df64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsAndHedgesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgesNoncurrent_5ea7341d-b61b-46fa-b865-19f17da5df64" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_f8a45847-e799-4eb8-9aaf-2c3f41610897" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_f8a45847-e799-4eb8-9aaf-2c3f41610897" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_2d17d973-ef60-4b76-83ad-935c146f1595" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_2d17d973-ef60-4b76-83ad-935c146f1595" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatedEntityOtherAssetsNoncurrent_6c5893ac-b77c-474e-a3e2-48415ecf7e43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RegulatedEntityOtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherAssetsNoncurrentAbstract_fceadec7-ffec-437d-8dac-34a27b8c8e5c" xlink:to="loc_us-gaap_RegulatedEntityOtherAssetsNoncurrent_6c5893ac-b77c-474e-a3e2-48415ecf7e43" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_0d99ad6c-a8e4-41f5-b7b5-580db00b2da7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_aa3f9053-4dc7-40e9-9ea5-d653635d88b5" xlink:to="loc_us-gaap_Assets_0d99ad6c-a8e4-41f5-b7b5-580db00b2da7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_2f87d2b8-2a25-480f-8db7-5b8c427d22d9" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_7cfe9a3f-4a8a-440c-9168-a2dc247a4422" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_7cfe9a3f-4a8a-440c-9168-a2dc247a4422" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_aa075935-f8a1-4345-bea8-b032aa06ba65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_aa075935-f8a1-4345-bea8-b032aa06ba65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_50b52721-6768-4dc8-8dc7-d49543551c42" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_us-gaap_AccountsPayableCurrent_50b52721-6768-4dc8-8dc7-d49543551c42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_cde5fd01-8d04-48db-9d2b-1d9032c64916" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_cde5fd01-8d04-48db-9d2b-1d9032c64916" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeAssetNotSubjectToMasterNettingArrangementCollateralObligationToReturnCashNotOffset_70214305-c97a-4f14-8ed6-80fab273f9d9" xlink:href="nrg-20231231.xsd#nrg_DerivativeAssetNotSubjectToMasterNettingArrangementCollateralObligationToReturnCashNotOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_nrg_DerivativeAssetNotSubjectToMasterNettingArrangementCollateralObligationToReturnCashNotOffset_70214305-c97a-4f14-8ed6-80fab273f9d9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_baadc899-ef76-4140-90d1-ac7c0d523a07" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_baadc899-ef76-4140-90d1-ac7c0d523a07" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_3f6f9afc-7ce3-42a8-935f-0a0b21d12c24" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_3f6f9afc-7ce3-42a8-935f-0a0b21d12c24" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_9c737ea5-dd47-45e7-ac45-641b6431493d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_680d7841-4c23-4d17-81d4-07fca1e0fce6" xlink:to="loc_us-gaap_LiabilitiesCurrent_9c737ea5-dd47-45e7-ac45-641b6431493d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_05376492-59f9-4136-bbe8-52e31002ee89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_05376492-59f9-4136-bbe8-52e31002ee89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_68731736-91d9-467c-9b46-66288d1d2f55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_68731736-91d9-467c-9b46-66288d1d2f55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningLiabilityNoncurrent_170cb07a-0937-405b-a7cf-0bea13b0da2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DecommissioningLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_DecommissioningLiabilityNoncurrent_170cb07a-0937-405b-a7cf-0bea13b0da2f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NuclearDecommissioningTrustFundLiabilityNoncurrent_57463267-7916-47c1-bdbc-ef8616291422" xlink:href="nrg-20231231.xsd#nrg_NuclearDecommissioningTrustFundLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_nrg_NuclearDecommissioningTrustFundLiabilityNoncurrent_57463267-7916-47c1-bdbc-ef8616291422" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_2e0ac926-b072-41cc-8cfd-d52bf26eba1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_2e0ac926-b072-41cc-8cfd-d52bf26eba1a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_d281d721-6f67-4468-ab13-791fc8732146" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_d281d721-6f67-4468-ab13-791fc8732146" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_cae34b6e-a951-484c-9f4c-36eedddfe0b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_cae34b6e-a951-484c-9f4c-36eedddfe0b1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_04073a24-6246-4663-b8fa-8ea9fefbca22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_04073a24-6246-4663-b8fa-8ea9fefbca22" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesNoncurrent_e56f8ec6-9678-45d3-98a8-e332f417a49a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_09270dca-a381-49ba-8f89-c97a0180006a" xlink:to="loc_us-gaap_LiabilitiesNoncurrent_e56f8ec6-9678-45d3-98a8-e332f417a49a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_b4c6c5f6-8655-498d-b167-c7052e06e0a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:to="loc_us-gaap_Liabilities_b4c6c5f6-8655-498d-b167-c7052e06e0a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_4566ce6c-1a64-4d3a-baf8-bdec08910011" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:to="loc_us-gaap_CommitmentsAndContingencies_4566ce6c-1a64-4d3a-baf8-bdec08910011" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:to="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_029a1ffa-abaf-4ae7-9f45-c5d3589ac4d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:to="loc_us-gaap_PreferredStockValue_029a1ffa-abaf-4ae7-9f45-c5d3589ac4d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_6e4c39a3-9b58-427a-82cf-798d252b10ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:to="loc_us-gaap_CommonStockValue_6e4c39a3-9b58-427a-82cf-798d252b10ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_9b1cee13-17c5-4333-bca4-24e5381952dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_9b1cee13-17c5-4333-bca4-24e5381952dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_fc52acf6-dfb8-4eeb-8709-3e56f8996fb1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_fc52acf6-dfb8-4eeb-8709-3e56f8996fb1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValue_c19666a9-204d-4442-b472-559cb2fce4a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:to="loc_us-gaap_TreasuryStockValue_c19666a9-204d-4442-b472-559cb2fce4a2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_443a4c9e-8dd7-4b34-8657-e8ce38360ca9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_443a4c9e-8dd7-4b34-8657-e8ce38360ca9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_242926ce-e10f-4762-a38c-6049d77576d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_bf1911f0-f87f-4830-8355-372bc0e53b92" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_242926ce-e10f-4762-a38c-6049d77576d2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_f0ff351e-30b6-4350-9bb2-2a92344816cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8e50770d-8008-4a12-92bb-2bce0ae20980" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_f0ff351e-30b6-4350-9bb2-2a92344816cd" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="nrg-20231231.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_e83b7052-da29-4fe0-9cfa-53628a944b31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_50b490da-438f-41e0-a599-f28445b7fdd1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_e83b7052-da29-4fe0-9cfa-53628a944b31" xlink:to="loc_us-gaap_StatementTable_50b490da-438f-41e0-a599-f28445b7fdd1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f0f318ec-7885-4da2-9a5c-df63cf559104" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_50b490da-438f-41e0-a599-f28445b7fdd1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f0f318ec-7885-4da2-9a5c-df63cf559104" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f0f318ec-7885-4da2-9a5c-df63cf559104_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f0f318ec-7885-4da2-9a5c-df63cf559104" xlink:to="loc_us-gaap_EquityComponentDomain_f0f318ec-7885-4da2-9a5c-df63cf559104_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f0f318ec-7885-4da2-9a5c-df63cf559104" xlink:to="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_098c0448-89f0-48a2-b776-c6a6b636e7ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:to="loc_us-gaap_PreferredStockMember_098c0448-89f0-48a2-b776-c6a6b636e7ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_3ded5929-3d7b-4181-be68-b739a33f5a7f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:to="loc_us-gaap_CommonStockMember_3ded5929-3d7b-4181-be68-b739a33f5a7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_05daf007-a79d-47f5-ac46-a0ff8bcaaf93" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_05daf007-a79d-47f5-ac46-a0ff8bcaaf93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_e4a36ca7-d2d6-4c4c-afb4-54071023ada2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:to="loc_us-gaap_RetainedEarningsMember_e4a36ca7-d2d6-4c4c-afb4-54071023ada2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_23ce8cc4-3c51-4217-b048-e71ad09f981a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:to="loc_us-gaap_TreasuryStockCommonMember_23ce8cc4-3c51-4217-b048-e71ad09f981a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_20f3c9a6-3876-4312-9b80-90b698a3d215" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_266fb2b9-beaf-4b99-9c43-6b033bd329b2" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_20f3c9a6-3876-4312-9b80-90b698a3d215" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ab9ceaab-c815-4b56-aee6-2b0629360023" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_50b490da-438f-41e0-a599-f28445b7fdd1" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ab9ceaab-c815-4b56-aee6-2b0629360023" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_ab9ceaab-c815-4b56-aee6-2b0629360023_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ab9ceaab-c815-4b56-aee6-2b0629360023" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_ab9ceaab-c815-4b56-aee6-2b0629360023_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_2840222d-07e7-4a07-a5c0-69bb11d2dd67" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_ab9ceaab-c815-4b56-aee6-2b0629360023" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_2840222d-07e7-4a07-a5c0-69bb11d2dd67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_a647d32c-b7e9-48cc-99b2-eabd63ac0129" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_2840222d-07e7-4a07-a5c0-69bb11d2dd67" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_a647d32c-b7e9-48cc-99b2-eabd63ac0129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_e83b7052-da29-4fe0-9cfa-53628a944b31" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_675492ce-6276-4eda-ad9a-c325fe2c35f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_675492ce-6276-4eda-ad9a-c325fe2c35f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest_677a3aad-eecc-41ce-9cbd-6360f765e676" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest_677a3aad-eecc-41ce-9cbd-6360f765e676" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_b30b90f3-5e8b-4069-b38e-d827b3d84720" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_b30b90f3-5e8b-4069-b38e-d827b3d84720" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_4e3207f7-86fc-41ca-81a3-7f4d5921fe32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_4e3207f7-86fc-41ca-81a3-7f4d5921fe32" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_e938d589-d253-43af-b9f4-80495ff177fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_e938d589-d253-43af-b9f4-80495ff177fe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_1c7def7b-1752-44fd-abee-3638e111a4bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_1c7def7b-1752-44fd-abee-3638e111a4bd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_21c6510f-416f-49f4-a4e2-807be050435f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockRetiredCostMethodAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_21c6510f-416f-49f4-a4e2-807be050435f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_32a614c8-0c8a-487e-97cb-9459a7d9013b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_32a614c8-0c8a-487e-97cb-9459a7d9013b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_45680727-3034-46d8-afd6-ce65877a48e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_45680727-3034-46d8-afd6-ce65877a48e1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_a3731dec-400e-4c9f-a6dc-94ea873a4eb1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_DividendsCommonStockCash_a3731dec-400e-4c9f-a6dc-94ea873a4eb1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockCash_ba42c976-e06d-43b6-abd3-b74f3233e2ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPreferredStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_DividendsPreferredStockCash_ba42c976-e06d-43b6-abd3-b74f3233e2ef" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_750f817c-8306-4cc3-85c7-291ca281fff2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_750f817c-8306-4cc3-85c7-291ca281fff2" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_747297b3-a4a6-4816-a4aa-c697a3d5d449" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdateExtensibleList_86d9880b-ce9d-463b-b344-643a1c2f98f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingStandardsUpdateExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2672fb24-ce30-4bf7-ba74-b46b67c3613b" xlink:to="loc_us-gaap_AccountingStandardsUpdateExtensibleList_86d9880b-ce9d-463b-b344-643a1c2f98f3" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParenthetical" xlink:type="simple" xlink:href="nrg-20231231.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParenthetical"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_d6071847-320d-4332-b9d2-d49dd5023e0f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_dc449b36-11cb-4299-a5a6-ce1a842632a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_d6071847-320d-4332-b9d2-d49dd5023e0f" xlink:to="loc_us-gaap_StatementTable_dc449b36-11cb-4299-a5a6-ce1a842632a0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_be314c93-3294-43ec-9b7a-ac113aab747e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_dc449b36-11cb-4299-a5a6-ce1a842632a0" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_be314c93-3294-43ec-9b7a-ac113aab747e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_be314c93-3294-43ec-9b7a-ac113aab747e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_be314c93-3294-43ec-9b7a-ac113aab747e" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_be314c93-3294-43ec-9b7a-ac113aab747e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_06236786-4d5a-4a79-9167-8de32ca250de" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_be314c93-3294-43ec-9b7a-ac113aab747e" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_06236786-4d5a-4a79-9167-8de32ca250de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_fc0064f1-ce89-4bf3-9ae6-9091d17b26ed" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_06236786-4d5a-4a79-9167-8de32ca250de" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_fc0064f1-ce89-4bf3-9ae6-9091d17b26ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_aaf77a84-bfa4-41ef-a4e7-7cafe0044010" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d6071847-320d-4332-b9d2-d49dd5023e0f" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_aaf77a84-bfa4-41ef-a4e7-7cafe0044010" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_843e2267-760e-4bd5-a1bb-5f67d643c8c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d6071847-320d-4332-b9d2-d49dd5023e0f" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_843e2267-760e-4bd5-a1bb-5f67d643c8c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareCashPaid_9835a983-c808-47e6-942f-71fd543c3ee8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d6071847-320d-4332-b9d2-d49dd5023e0f" xlink:to="loc_us-gaap_CommonStockDividendsPerShareCashPaid_9835a983-c808-47e6-942f-71fd543c3ee8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TreasuryStockValueAcquiredCostMethodExciseTax_c4a32443-9345-474f-9512-7599d192d422" xlink:href="nrg-20231231.xsd#nrg_TreasuryStockValueAcquiredCostMethodExciseTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d6071847-320d-4332-b9d2-d49dd5023e0f" xlink:to="loc_nrg_TreasuryStockValueAcquiredCostMethodExciseTax_c4a32443-9345-474f-9512-7599d192d422" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_a99a0def-3198-41a3-9935-62b4c2f5d556" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d6071847-320d-4332-b9d2-d49dd5023e0f" xlink:to="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_a99a0def-3198-41a3-9935-62b4c2f5d556" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/NatureofBusinessDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#NatureofBusinessDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/NatureofBusinessDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_f0e22af0-6c44-4b3c-91f0-7c80e794231b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_78ff671f-d943-4d95-911e-b88fc3bb087b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0e22af0-6c44-4b3c-91f0-7c80e794231b" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_78ff671f-d943-4d95-911e-b88fc3bb087b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_85d8686a-cc74-40a3-a8c2-d86c30e8f311" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_78ff671f-d943-4d95-911e-b88fc3bb087b" xlink:to="loc_srt_MajorCustomersAxis_85d8686a-cc74-40a3-a8c2-d86c30e8f311" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_85d8686a-cc74-40a3-a8c2-d86c30e8f311_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_85d8686a-cc74-40a3-a8c2-d86c30e8f311" xlink:to="loc_srt_NameOfMajorCustomerDomain_85d8686a-cc74-40a3-a8c2-d86c30e8f311_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_661f496e-741b-4773-951c-cb7a4b75d9de" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_85d8686a-cc74-40a3-a8c2-d86c30e8f311" xlink:to="loc_srt_NameOfMajorCustomerDomain_661f496e-741b-4773-951c-cb7a4b75d9de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_HomeCustomerMember_6671cd1f-2212-4a02-b741-7785c66ba0b9" xlink:href="nrg-20231231.xsd#nrg_HomeCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_661f496e-741b-4773-951c-cb7a4b75d9de" xlink:to="loc_nrg_HomeCustomerMember_6671cd1f-2212-4a02-b741-7785c66ba0b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfCustomers_5e96dd74-6baa-4187-a0a7-e55dadddd1ed" xlink:href="nrg-20231231.xsd#nrg_NumberOfCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0e22af0-6c44-4b3c-91f0-7c80e794231b" xlink:to="loc_nrg_NumberOfCustomers_5e96dd74-6baa-4187-a0a7-e55dadddd1ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PowerGenerationCapacityMegawatts_9f2c3820-e528-42ee-ae49-49990be57510" xlink:href="nrg-20231231.xsd#nrg_PowerGenerationCapacityMegawatts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_f0e22af0-6c44-4b3c-91f0-7c80e794231b" xlink:to="loc_nrg_PowerGenerationCapacityMegawatts_9f2c3820-e528-42ee-ae49-49990be57510" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesErrorCorrectionDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#SummaryofSignificantAccountingPoliciesErrorCorrectionDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesErrorCorrectionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_163e91bf-0290-44aa-a239-6ff8c12d6d0f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_252175cd-5643-45f6-88ff-3c9c20fcfdd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_163e91bf-0290-44aa-a239-6ff8c12d6d0f" xlink:to="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_252175cd-5643-45f6-88ff-3c9c20fcfdd9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_83f7daef-a17b-47bb-a435-31779c3a36c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_252175cd-5643-45f6-88ff-3c9c20fcfdd9" xlink:to="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_83f7daef-a17b-47bb-a435-31779c3a36c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_83f7daef-a17b-47bb-a435-31779c3a36c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsForErrorCorrectionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_83f7daef-a17b-47bb-a435-31779c3a36c0" xlink:to="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_83f7daef-a17b-47bb-a435-31779c3a36c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_29b96157-5d4f-4291-bbc6-5005062b7f20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsForErrorCorrectionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementByRestatementPeriodAndAmountAxis_83f7daef-a17b-47bb-a435-31779c3a36c0" xlink:to="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_29b96157-5d4f-4291-bbc6-5005062b7f20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ErrorCorrectionOtherMember_a145cb09-b75a-4718-a375-963424dcffe8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ErrorCorrectionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsForErrorCorrectionDomain_29b96157-5d4f-4291-bbc6-5005062b7f20" xlink:to="loc_us-gaap_ErrorCorrectionOtherMember_a145cb09-b75a-4718-a375-963424dcffe8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_2d0c2e1f-f80a-49ff-a90e-2367c44e6dc9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_163e91bf-0290-44aa-a239-6ff8c12d6d0f" xlink:to="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_2d0c2e1f-f80a-49ff-a90e-2367c44e6dc9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_7f913109-19c1-48d3-b803-f80db95a973b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_163e91bf-0290-44aa-a239-6ff8c12d6d0f" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_7f913109-19c1-48d3-b803-f80db95a973b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesActivityintheAllowanceforCreditLossesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#SummaryofSignificantAccountingPoliciesActivityintheAllowanceforCreditLossesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesActivityintheAllowanceforCreditLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SummaryOfSignificantAccountingPoliciesLineItems_b0dc278b-f9d9-4694-beec-bd9533696ceb" xlink:href="nrg-20231231.xsd#nrg_SummaryOfSignificantAccountingPoliciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SummaryofSignificantAccountingPoliciesTable_c927de88-5ffd-4006-b438-74db072c6daa" xlink:href="nrg-20231231.xsd#nrg_SummaryofSignificantAccountingPoliciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nrg_SummaryOfSignificantAccountingPoliciesLineItems_b0dc278b-f9d9-4694-beec-bd9533696ceb" xlink:to="loc_nrg_SummaryofSignificantAccountingPoliciesTable_c927de88-5ffd-4006-b438-74db072c6daa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_2eea9986-ede6-4ced-80a6-5483f9849065" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_SummaryofSignificantAccountingPoliciesTable_c927de88-5ffd-4006-b438-74db072c6daa" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_2eea9986-ede6-4ced-80a6-5483f9849065" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2eea9986-ede6-4ced-80a6-5483f9849065_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2eea9986-ede6-4ced-80a6-5483f9849065" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2eea9986-ede6-4ced-80a6-5483f9849065_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2582b9c7-875e-4e46-9879-f1b942018aa9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2eea9986-ede6-4ced-80a6-5483f9849065" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2582b9c7-875e-4e46-9879-f1b942018aa9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSmartHomeIncMember_529826bf-04d4-4464-934c-cdb3ba7dec1b" xlink:href="nrg-20231231.xsd#nrg_VivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2582b9c7-875e-4e46-9879-f1b942018aa9" xlink:to="loc_nrg_VivintSmartHomeIncMember_529826bf-04d4-4464-934c-cdb3ba7dec1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DirectEnergyMember_84b852f9-7ab0-4d40-9476-829ec86edff4" xlink:href="nrg-20231231.xsd#nrg_DirectEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2582b9c7-875e-4e46-9879-f1b942018aa9" xlink:to="loc_nrg_DirectEnergyMember_84b852f9-7ab0-4d40-9476-829ec86edff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SummaryOfSignificantAccountingPoliciesLineItems_b0dc278b-f9d9-4694-beec-bd9533696ceb" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_e117a2c7-f926-4d59-9042-3be48d8a17e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_e117a2c7-f926-4d59-9042-3be48d8a17e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccountsReceivableAllowanceForCreditLossAcquiredInAcquisition_dd42c093-34ea-4f36-8b19-fbec1b86f886" xlink:href="nrg-20231231.xsd#nrg_AccountsReceivableAllowanceForCreditLossAcquiredInAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:to="loc_nrg_AccountsReceivableAllowanceForCreditLossAcquiredInAcquisition_dd42c093-34ea-4f36-8b19-fbec1b86f886" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_24d4b07b-631c-44f2-a9ae-f33eee3a7305" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_24d4b07b-631c-44f2-a9ae-f33eee3a7305" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_f9186210-b608-4115-959e-ddd14399292e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_f9186210-b608-4115-959e-ddd14399292e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRecoveries_e4f956a3-95c3-4227-a146-16b05d0988b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableRecoveries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRecoveries_e4f956a3-95c3-4227-a146-16b05d0988b5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccountsReceivableAllowanceForCreditLossOther_5872dc56-5a5e-47a3-8849-96e0873f312b" xlink:href="nrg-20231231.xsd#nrg_AccountsReceivableAllowanceForCreditLossOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:to="loc_nrg_AccountsReceivableAllowanceForCreditLossOther_5872dc56-5a5e-47a3-8849-96e0873f312b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_51567715-2710-497f-8412-22e00253ec2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccountsReceivableAllowanceForCreditLossIncreaseDecreaseDueFinanceHedgeRisk_a504347e-56e6-444d-8d36-201cac347397" xlink:href="nrg-20231231.xsd#nrg_AccountsReceivableAllowanceForCreditLossIncreaseDecreaseDueFinanceHedgeRisk"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_b35ef792-8273-48b1-ad89-de9978e1e927" xlink:to="loc_nrg_AccountsReceivableAllowanceForCreditLossIncreaseDecreaseDueFinanceHedgeRisk_a504347e-56e6-444d-8d36-201cac347397" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesCreditLossesNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#SummaryofSignificantAccountingPoliciesCreditLossesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesCreditLossesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SummaryOfSignificantAccountingPoliciesLineItems_8dbff3a8-2f0a-4547-a7b2-dc18138638d8" xlink:href="nrg-20231231.xsd#nrg_SummaryOfSignificantAccountingPoliciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SummaryofSignificantAccountingPoliciesTable_362930b6-77bb-4d9c-9c8f-4a75000b94c2" xlink:href="nrg-20231231.xsd#nrg_SummaryofSignificantAccountingPoliciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nrg_SummaryOfSignificantAccountingPoliciesLineItems_8dbff3a8-2f0a-4547-a7b2-dc18138638d8" xlink:to="loc_nrg_SummaryofSignificantAccountingPoliciesTable_362930b6-77bb-4d9c-9c8f-4a75000b94c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_14e4ee1b-6ad8-4b4e-babc-825412511ace" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_SummaryofSignificantAccountingPoliciesTable_362930b6-77bb-4d9c-9c8f-4a75000b94c2" xlink:to="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_14e4ee1b-6ad8-4b4e-babc-825412511ace" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CatastrophicEventDomain_14e4ee1b-6ad8-4b4e-babc-825412511ace_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CatastrophicEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_14e4ee1b-6ad8-4b4e-babc-825412511ace" xlink:to="loc_us-gaap_CatastrophicEventDomain_14e4ee1b-6ad8-4b4e-babc-825412511ace_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CatastrophicEventDomain_aca5f7f3-c02b-467b-ae29-cf9b21e112c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CatastrophicEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_14e4ee1b-6ad8-4b4e-babc-825412511ace" xlink:to="loc_us-gaap_CatastrophicEventDomain_aca5f7f3-c02b-467b-ae29-cf9b21e112c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WinterStormUriMember_27c34ccc-7c38-44a0-a769-9d6bcb21a086" xlink:href="nrg-20231231.xsd#nrg_WinterStormUriMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CatastrophicEventDomain_aca5f7f3-c02b-467b-ae29-cf9b21e112c1" xlink:to="loc_nrg_WinterStormUriMember_27c34ccc-7c38-44a0-a769-9d6bcb21a086" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_072bc262-832a-4c5d-a30a-2f069c2b2337" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SummaryOfSignificantAccountingPoliciesLineItems_8dbff3a8-2f0a-4547-a7b2-dc18138638d8" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_072bc262-832a-4c5d-a30a-2f069c2b2337" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesVivintFlexPayandCapitalizedContractCostsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#SummaryofSignificantAccountingPoliciesVivintFlexPayandCapitalizedContractCostsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/SummaryofSignificantAccountingPoliciesVivintFlexPayandCapitalizedContractCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductInformationLineItems_775777ab-e265-4d2e-8e06-62bc14b9035f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfProductInformationTable_45d0e71c-05d0-43c8-bfd1-63409ba82cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfProductInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductInformationLineItems_775777ab-e265-4d2e-8e06-62bc14b9035f" xlink:to="loc_us-gaap_ScheduleOfProductInformationTable_45d0e71c-05d0-43c8-bfd1-63409ba82cfe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_af4a39e1-7af0-4564-9eb5-f7c8793a7343" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_45d0e71c-05d0-43c8-bfd1-63409ba82cfe" xlink:to="loc_dei_LegalEntityAxis_af4a39e1-7af0-4564-9eb5-f7c8793a7343" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_af4a39e1-7af0-4564-9eb5-f7c8793a7343_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_af4a39e1-7af0-4564-9eb5-f7c8793a7343" xlink:to="loc_dei_EntityDomain_af4a39e1-7af0-4564-9eb5-f7c8793a7343_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_97f1696a-5be5-4675-bf33-d9611b2318c5" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_af4a39e1-7af0-4564-9eb5-f7c8793a7343" xlink:to="loc_dei_EntityDomain_97f1696a-5be5-4675-bf33-d9611b2318c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSmartHomeIncMember_4f3acdfd-fc01-4809-a4d1-a33f6d8f1227" xlink:href="nrg-20231231.xsd#nrg_VivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_97f1696a-5be5-4675-bf33-d9611b2318c5" xlink:to="loc_nrg_VivintSmartHomeIncMember_4f3acdfd-fc01-4809-a4d1-a33f6d8f1227" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_37b71433-49fe-46a7-92eb-9a68ebe2e487" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfProductInformationTable_45d0e71c-05d0-43c8-bfd1-63409ba82cfe" xlink:to="loc_srt_RangeAxis_37b71433-49fe-46a7-92eb-9a68ebe2e487" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_37b71433-49fe-46a7-92eb-9a68ebe2e487_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_37b71433-49fe-46a7-92eb-9a68ebe2e487" xlink:to="loc_srt_RangeMember_37b71433-49fe-46a7-92eb-9a68ebe2e487_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0eb21e07-0a0d-4bac-ab65-1c839ccf5677" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_37b71433-49fe-46a7-92eb-9a68ebe2e487" xlink:to="loc_srt_RangeMember_0eb21e07-0a0d-4bac-ab65-1c839ccf5677" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_2d296dce-9188-4990-8f50-d6b6172c0cc8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0eb21e07-0a0d-4bac-ab65-1c839ccf5677" xlink:to="loc_srt_MinimumMember_2d296dce-9188-4990-8f50-d6b6172c0cc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_0bc677ca-08b2-442c-a349-98102740d39f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0eb21e07-0a0d-4bac-ab65-1c839ccf5677" xlink:to="loc_srt_MaximumMember_0bc677ca-08b2-442c-a349-98102740d39f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ContractWithCustomerCustomerShortTermFinancingTerm_66398f1d-07e7-43aa-a77c-b15a0415829f" xlink:href="nrg-20231231.xsd#nrg_ContractWithCustomerCustomerShortTermFinancingTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_775777ab-e265-4d2e-8e06-62bc14b9035f" xlink:to="loc_nrg_ContractWithCustomerCustomerShortTermFinancingTerm_66398f1d-07e7-43aa-a77c-b15a0415829f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfPerformanceObligations_a26cee08-65a8-4235-adb8-3a94b3f93174" xlink:href="nrg-20231231.xsd#nrg_NumberOfPerformanceObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_775777ab-e265-4d2e-8e06-62bc14b9035f" xlink:to="loc_nrg_NumberOfPerformanceObligations_a26cee08-65a8-4235-adb8-3a94b3f93174" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FinanceProviderLoansIssuedCustomerRepaymentTerm_d707f3b1-0c38-44cc-89a7-19d530214025" xlink:href="nrg-20231231.xsd#nrg_FinanceProviderLoansIssuedCustomerRepaymentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_775777ab-e265-4d2e-8e06-62bc14b9035f" xlink:to="loc_nrg_FinanceProviderLoansIssuedCustomerRepaymentTerm_d707f3b1-0c38-44cc-89a7-19d530214025" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FinancingProviderLoansLiabilityForCustomerLostPrincipleBalancesPercentage_bc3b51b3-0d5e-4b2a-9992-8cd5a8fe7392" xlink:href="nrg-20231231.xsd#nrg_FinancingProviderLoansLiabilityForCustomerLostPrincipleBalancesPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_775777ab-e265-4d2e-8e06-62bc14b9035f" xlink:to="loc_nrg_FinancingProviderLoansLiabilityForCustomerLostPrincipleBalancesPercentage_bc3b51b3-0d5e-4b2a-9992-8cd5a8fe7392" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RevenueRecognitionRetailRevenueDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#RevenueRecognitionRetailRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RevenueRecognitionRetailRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_3c028090-5ccf-42a1-bfa8-efd21d82e4a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_e5a9f33e-19a0-4837-9ee0-9d9a352adc8f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3c028090-5ccf-42a1-bfa8-efd21d82e4a8" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_e5a9f33e-19a0-4837-9ee0-9d9a352adc8f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6888d7db-11a0-469a-a600-0692c99142d7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e5a9f33e-19a0-4837-9ee0-9d9a352adc8f" xlink:to="loc_srt_RangeAxis_6888d7db-11a0-469a-a600-0692c99142d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6888d7db-11a0-469a-a600-0692c99142d7_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6888d7db-11a0-469a-a600-0692c99142d7" xlink:to="loc_srt_RangeMember_6888d7db-11a0-469a-a600-0692c99142d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_378d6c13-cdb6-4e46-93b1-a54c85c158bc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6888d7db-11a0-469a-a600-0692c99142d7" xlink:to="loc_srt_RangeMember_378d6c13-cdb6-4e46-93b1-a54c85c158bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_9fba8747-5699-4579-8d2a-a6207512753b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_378d6c13-cdb6-4e46-93b1-a54c85c158bc" xlink:to="loc_srt_MinimumMember_9fba8747-5699-4579-8d2a-a6207512753b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_bc00ea01-9b11-49b7-a073-25c1975da26f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_378d6c13-cdb6-4e46-93b1-a54c85c158bc" xlink:to="loc_srt_MaximumMember_bc00ea01-9b11-49b7-a073-25c1975da26f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_6bb5568a-a856-46ba-b6d0-fef6b9016eb9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e5a9f33e-19a0-4837-9ee0-9d9a352adc8f" xlink:to="loc_srt_ProductOrServiceAxis_6bb5568a-a856-46ba-b6d0-fef6b9016eb9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6bb5568a-a856-46ba-b6d0-fef6b9016eb9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_6bb5568a-a856-46ba-b6d0-fef6b9016eb9" xlink:to="loc_srt_ProductsAndServicesDomain_6bb5568a-a856-46ba-b6d0-fef6b9016eb9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_99bbd290-8a03-491f-933e-b5ea555979fd" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_6bb5568a-a856-46ba-b6d0-fef6b9016eb9" xlink:to="loc_srt_ProductsAndServicesDomain_99bbd290-8a03-491f-933e-b5ea555979fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProductsAndServicesRetailRevenueMember_b7461e2c-e2ca-4507-adc0-12fcd6a5df9f" xlink:href="nrg-20231231.xsd#nrg_ProductsAndServicesRetailRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_99bbd290-8a03-491f-933e-b5ea555979fd" xlink:to="loc_nrg_ProductsAndServicesRetailRevenueMember_b7461e2c-e2ca-4507-adc0-12fcd6a5df9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintHomeServicesMember_6120a2a4-527c-42d9-937f-0b24b57353d1" xlink:href="nrg-20231231.xsd#nrg_VivintHomeServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_99bbd290-8a03-491f-933e-b5ea555979fd" xlink:to="loc_nrg_VivintHomeServicesMember_6120a2a4-527c-42d9-937f-0b24b57353d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EnergyRevenueMember_405e06ed-8a8b-45d6-8db2-5645ec6a1c76" xlink:href="nrg-20231231.xsd#nrg_EnergyRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_99bbd290-8a03-491f-933e-b5ea555979fd" xlink:to="loc_nrg_EnergyRevenueMember_405e06ed-8a8b-45d6-8db2-5645ec6a1c76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapacityRevenueMember_c944442a-5f2e-46a8-8dce-f8302d828da1" xlink:href="nrg-20231231.xsd#nrg_CapacityRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_99bbd290-8a03-491f-933e-b5ea555979fd" xlink:to="loc_nrg_CapacityRevenueMember_c944442a-5f2e-46a8-8dce-f8302d828da1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ContractWithCustomerPaymentTermPeriod_f1a1cb17-532a-43d7-9524-1950bc765184" xlink:href="nrg-20231231.xsd#nrg_ContractWithCustomerPaymentTermPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3c028090-5ccf-42a1-bfa8-efd21d82e4a8" xlink:to="loc_nrg_ContractWithCustomerPaymentTermPeriod_f1a1cb17-532a-43d7-9524-1950bc765184" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuePerformanceObligationDescriptionOfTiming_fa57a69a-ff8e-4e04-985a-205dd8942df6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuePerformanceObligationDescriptionOfTiming"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_3c028090-5ccf-42a1-bfa8-efd21d82e4a8" xlink:to="loc_us-gaap_RevenuePerformanceObligationDescriptionOfTiming_fa57a69a-ff8e-4e04-985a-205dd8942df6" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RevenueRecognitionPerformanceObligationsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#RevenueRecognitionPerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RevenueRecognitionPerformanceObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_435533c8-e403-42bd-8d60-3b3d3f5462f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_435533c8-e403-42bd-8d60-3b3d3f5462f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_d9dc5fc4-bcce-4eba-999f-9159acb91287" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_435533c8-e403-42bd-8d60-3b3d3f5462f6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_d9dc5fc4-bcce-4eba-999f-9159acb91287" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_1bfe5741-08b6-4f89-8502-69a930fd33fa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_1bfe5741-08b6-4f89-8502-69a930fd33fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_60b8220a-62ae-4661-8a1c-311f6baed1ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_60b8220a-62ae-4661-8a1c-311f6baed1ec" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RevenueRecognitionPerformanceObligationsDetails_1" xlink:type="simple" xlink:href="nrg-20231231.xsd#RevenueRecognitionPerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RevenueRecognitionPerformanceObligationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_435533c8-e403-42bd-8d60-3b3d3f5462f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_435533c8-e403-42bd-8d60-3b3d3f5462f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_1bfe5741-08b6-4f89-8502-69a930fd33fa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_1bfe5741-08b6-4f89-8502-69a930fd33fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_60b8220a-62ae-4661-8a1c-311f6baed1ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dcca430a-63e2-4b21-9bc5-fc9daa99a0be" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_60b8220a-62ae-4661-8a1c-311f6baed1ec" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RevenueRecognitionDisaggregatedRevenuesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#RevenueRecognitionDisaggregatedRevenuesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RevenueRecognitionDisaggregatedRevenuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_6a514b32-9754-4cde-b71e-a80d37047a5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_6a514b32-9754-4cde-b71e-a80d37047a5b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_a3e7918e-834f-4eef-9218-07b4aa51ab19" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6a514b32-9754-4cde-b71e-a80d37047a5b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_a3e7918e-834f-4eef-9218-07b4aa51ab19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a3e7918e-834f-4eef-9218-07b4aa51ab19_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_a3e7918e-834f-4eef-9218-07b4aa51ab19" xlink:to="loc_us-gaap_SegmentDomain_a3e7918e-834f-4eef-9218-07b4aa51ab19_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_53d35c87-53bc-4b16-9d28-c4d724489f58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_a3e7918e-834f-4eef-9218-07b4aa51ab19" xlink:to="loc_us-gaap_SegmentDomain_53d35c87-53bc-4b16-9d28-c4d724489f58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TexasSegmentMember_8713395f-c8c9-408c-af56-99a6c111d9ba" xlink:href="nrg-20231231.xsd#nrg_TexasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_53d35c87-53bc-4b16-9d28-c4d724489f58" xlink:to="loc_nrg_TexasSegmentMember_8713395f-c8c9-408c-af56-99a6c111d9ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EastSegmentMember_1b3fa6a0-20c8-4478-a18d-2bcc98c2d152" xlink:href="nrg-20231231.xsd#nrg_EastSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_53d35c87-53bc-4b16-9d28-c4d724489f58" xlink:to="loc_nrg_EastSegmentMember_1b3fa6a0-20c8-4478-a18d-2bcc98c2d152" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WestServicesAndOtherSegmentMember_418a29aa-c448-4053-90e0-382424a0efdc" xlink:href="nrg-20231231.xsd#nrg_WestServicesAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_53d35c87-53bc-4b16-9d28-c4d724489f58" xlink:to="loc_nrg_WestServicesAndOtherSegmentMember_418a29aa-c448-4053-90e0-382424a0efdc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSmartHomeIncMember_6462d45c-50ba-4aa6-8307-cb9e91e354e5" xlink:href="nrg-20231231.xsd#nrg_VivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_53d35c87-53bc-4b16-9d28-c4d724489f58" xlink:to="loc_nrg_VivintSmartHomeIncMember_6462d45c-50ba-4aa6-8307-cb9e91e354e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_8b03c4e7-1c6c-4efb-9ab6-d5aa71b5e8fc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6a514b32-9754-4cde-b71e-a80d37047a5b" xlink:to="loc_srt_ConsolidationItemsAxis_8b03c4e7-1c6c-4efb-9ab6-d5aa71b5e8fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_8b03c4e7-1c6c-4efb-9ab6-d5aa71b5e8fc_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_8b03c4e7-1c6c-4efb-9ab6-d5aa71b5e8fc" xlink:to="loc_srt_ConsolidationItemsDomain_8b03c4e7-1c6c-4efb-9ab6-d5aa71b5e8fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_be388599-dc0c-4efb-adf2-2a80d3b06cc2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_8b03c4e7-1c6c-4efb-9ab6-d5aa71b5e8fc" xlink:to="loc_srt_ConsolidationItemsDomain_be388599-dc0c-4efb-adf2-2a80d3b06cc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_ec0842ee-7857-4336-a571-deb1c78367f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_be388599-dc0c-4efb-adf2-2a80d3b06cc2" xlink:to="loc_us-gaap_OperatingSegmentsMember_ec0842ee-7857-4336-a571-deb1c78367f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_497ad0c4-d07f-4669-96ce-e084322bc84f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_be388599-dc0c-4efb-adf2-2a80d3b06cc2" xlink:to="loc_us-gaap_IntersegmentEliminationMember_497ad0c4-d07f-4669-96ce-e084322bc84f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_3dc3bec0-ea7a-4312-92e5-2238e351999b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6a514b32-9754-4cde-b71e-a80d37047a5b" xlink:to="loc_srt_ProductOrServiceAxis_3dc3bec0-ea7a-4312-92e5-2238e351999b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3dc3bec0-ea7a-4312-92e5-2238e351999b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_3dc3bec0-ea7a-4312-92e5-2238e351999b" xlink:to="loc_srt_ProductsAndServicesDomain_3dc3bec0-ea7a-4312-92e5-2238e351999b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_3dc3bec0-ea7a-4312-92e5-2238e351999b" xlink:to="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProductsAndServicesRetailRevenueMember_c3ffafb9-a356-47f6-abf9-06c8fd5a9c02" xlink:href="nrg-20231231.xsd#nrg_ProductsAndServicesRetailRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_ProductsAndServicesRetailRevenueMember_c3ffafb9-a356-47f6-abf9-06c8fd5a9c02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProductsAndServicesTotalRetailMember_421c5497-3707-412e-ac94-584d7890a64f" xlink:href="nrg-20231231.xsd#nrg_ProductsAndServicesTotalRetailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_ProductsAndServicesTotalRetailMember_421c5497-3707-412e-ac94-584d7890a64f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EnergyRevenueMember_d079897b-eadb-4a5d-a1bb-195a29afca58" xlink:href="nrg-20231231.xsd#nrg_EnergyRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_EnergyRevenueMember_d079897b-eadb-4a5d-a1bb-195a29afca58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapacityRevenueMember_dd47c1c7-e021-4f3a-8b37-47ceb45cdf75" xlink:href="nrg-20231231.xsd#nrg_CapacityRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_CapacityRevenueMember_dd47c1c7-e021-4f3a-8b37-47ceb45cdf75" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProductsAndServicesDerivativeRevenueMember_c6f53eac-6453-4e68-8b6e-af525f01766c" xlink:href="nrg-20231231.xsd#nrg_ProductsAndServicesDerivativeRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_ProductsAndServicesDerivativeRevenueMember_c6f53eac-6453-4e68-8b6e-af525f01766c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProductsAndServicesOtherMember_f41c3417-37f7-477b-916a-a7618c10aec6" xlink:href="nrg-20231231.xsd#nrg_ProductsAndServicesOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_ProductsAndServicesOtherMember_f41c3417-37f7-477b-916a-a7618c10aec6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OperatingRevenuesMember_6e105111-27a9-4896-96c6-d81005d8f171" xlink:href="nrg-20231231.xsd#nrg_OperatingRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_OperatingRevenuesMember_6e105111-27a9-4896-96c6-d81005d8f171" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProductsAndServicesOtherAncillaryMember_e6da034e-caaf-4df3-8126-063e123996ca" xlink:href="nrg-20231231.xsd#nrg_ProductsAndServicesOtherAncillaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_ProductsAndServicesOtherAncillaryMember_e6da034e-caaf-4df3-8126-063e123996ca" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProductsAndServicesOtherDerivativeRevenueMember_cdf3fda3-9e96-4515-8d61-744e3b6142ef" xlink:href="nrg-20231231.xsd#nrg_ProductsAndServicesOtherDerivativeRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f1d633f1-b790-4965-a533-df10dad29560" xlink:to="loc_nrg_ProductsAndServicesOtherDerivativeRevenueMember_cdf3fda3-9e96-4515-8d61-744e3b6142ef" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_76098655-cfa7-427a-97e6-ba56987cc37d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6a514b32-9754-4cde-b71e-a80d37047a5b" xlink:to="loc_srt_MajorCustomersAxis_76098655-cfa7-427a-97e6-ba56987cc37d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_76098655-cfa7-427a-97e6-ba56987cc37d_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_76098655-cfa7-427a-97e6-ba56987cc37d" xlink:to="loc_srt_NameOfMajorCustomerDomain_76098655-cfa7-427a-97e6-ba56987cc37d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_2ce25116-1e75-4d7a-91f2-69edd5453573" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_76098655-cfa7-427a-97e6-ba56987cc37d" xlink:to="loc_srt_NameOfMajorCustomerDomain_2ce25116-1e75-4d7a-91f2-69edd5453573" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_HomeCustomerMember_9d9040f8-a52a-47dd-90be-2cca8c9b4b72" xlink:href="nrg-20231231.xsd#nrg_HomeCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_2ce25116-1e75-4d7a-91f2-69edd5453573" xlink:to="loc_nrg_HomeCustomerMember_9d9040f8-a52a-47dd-90be-2cca8c9b4b72" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessSolutionsCustomersMember_e01d6ae3-8f62-46d7-b0e1-1a79e6605e9a" xlink:href="nrg-20231231.xsd#nrg_BusinessSolutionsCustomersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_2ce25116-1e75-4d7a-91f2-69edd5453573" xlink:to="loc_nrg_BusinessSolutionsCustomersMember_e01d6ae3-8f62-46d7-b0e1-1a79e6605e9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_bf2265e2-ea85-4444-ba80-0c62fd17fee2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_bf2265e2-ea85-4444-ba80-0c62fd17fee2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_UnrealizedGainLossOnDerivativesMarkToMarketEconomicHedgingActivities_b61ef21d-251b-401f-b2b9-f07632697d55" xlink:href="nrg-20231231.xsd#nrg_UnrealizedGainLossOnDerivativesMarkToMarketEconomicHedgingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_nrg_UnrealizedGainLossOnDerivativesMarkToMarketEconomicHedgingActivities_b61ef21d-251b-401f-b2b9-f07632697d55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortization_01d9de0c-01f6-4a23-b7ad-c6f59c1387b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalizedContractCostAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_us-gaap_CapitalizedContractCostAmortization_01d9de0c-01f6-4a23-b7ad-c6f59c1387b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_594fc2da-e262-4a38-a16b-d772d9221fdf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_us-gaap_Revenues_594fc2da-e262-4a38-a16b-d772d9221fdf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueNotFromContractWithCustomerOther_b1978db2-223e-43a4-96c7-162d87ff7811" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueNotFromContractWithCustomerOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_us-gaap_RevenueNotFromContractWithCustomerOther_b1978db2-223e-43a4-96c7-162d87ff7811" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_af7480c3-5ee9-4818-90b9-4c11401d91d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnDerivativeInstrumentsNetPretax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_af7480c3-5ee9-4818-90b9-4c11401d91d9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_40314896-d304-4011-bf93-7a1aaba36d6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_5ba81b4f-b8e4-4351-9609-61015dbd0630" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_40314896-d304-4011-bf93-7a1aaba36d6e" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RevenueRecognitionContractBalancesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#RevenueRecognitionContractBalancesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RevenueRecognitionContractBalancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:href="nrg-20231231.xsd#nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesTable_a25378d4-3db1-4d60-8d14-9e5eab3686ad" xlink:href="nrg-20231231.xsd#nrg_ScheduleOfContractAssetsAndLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:to="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesTable_a25378d4-3db1-4d60-8d14-9e5eab3686ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e2417203-5d60-477f-acaf-15093daf7b00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesTable_a25378d4-3db1-4d60-8d14-9e5eab3686ad" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e2417203-5d60-477f-acaf-15093daf7b00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_e2417203-5d60-477f-acaf-15093daf7b00_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e2417203-5d60-477f-acaf-15093daf7b00" xlink:to="loc_us-gaap_ReceivableTypeDomain_e2417203-5d60-477f-acaf-15093daf7b00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_49d3abf2-635e-438e-a2bb-999273c05976" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_e2417203-5d60-477f-acaf-15093daf7b00" xlink:to="loc_us-gaap_ReceivableTypeDomain_49d3abf2-635e-438e-a2bb-999273c05976" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerContractsMember_0aa9e409-8a5e-436d-904a-df46870159d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_49d3abf2-635e-438e-a2bb-999273c05976" xlink:to="loc_us-gaap_CustomerContractsMember_0aa9e409-8a5e-436d-904a-df46870159d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NonASC606Member_31ca0d19-d7cc-4fa3-8822-a4b29c614b42" xlink:href="nrg-20231231.xsd#nrg_NonASC606Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_49d3abf2-635e-438e-a2bb-999273c05976" xlink:to="loc_nrg_NonASC606Member_31ca0d19-d7cc-4fa3-8822-a4b29c614b42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_03475277-6b10-4ede-bf28-9d51b0b8e530" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_49d3abf2-635e-438e-a2bb-999273c05976" xlink:to="loc_srt_AffiliatedEntityMember_03475277-6b10-4ede-bf28-9d51b0b8e530" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostNet_b29411a2-a035-48e8-8734-9e82c6ecfd96" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalizedContractCostNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:to="loc_us-gaap_CapitalizedContractCostNet_b29411a2-a035-48e8-8734-9e82c6ecfd96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNet_668f1d6b-eb5b-4d2d-9e05-6eea03162c0c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:to="loc_us-gaap_AccountsReceivableNet_668f1d6b-eb5b-4d2d-9e05-6eea03162c0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnbilledContractsReceivable_6fbf2514-f9be-436f-9980-fbc5b55930b2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnbilledContractsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:to="loc_us-gaap_UnbilledContractsReceivable_6fbf2514-f9be-436f-9980-fbc5b55930b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_0f3ec355-37de-45f1-b397-2765b890f295" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:to="loc_us-gaap_ContractWithCustomerLiability_0f3ec355-37de-45f1-b397-2765b890f295" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortization_298fc48f-030d-41be-a400-610e694c2c13" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalizedContractCostAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:to="loc_us-gaap_CapitalizedContractCostAmortization_298fc48f-030d-41be-a400-610e694c2c13" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ContractwithCustomerLiabilityIncreaseForCashPaymentsReceived_10090109-8cf6-44fe-9f6e-3dac5c80542c" xlink:href="nrg-20231231.xsd#nrg_ContractwithCustomerLiabilityIncreaseForCashPaymentsReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_ce2074d0-7f68-4895-b1eb-abcb31d02c53" xlink:to="loc_nrg_ContractwithCustomerLiabilityIncreaseForCashPaymentsReceived_10090109-8cf6-44fe-9f6e-3dac5c80542c" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RevenueRecognitionNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#RevenueRecognitionNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RevenueRecognitionNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_25fdef14-4fcf-44c6-b6ec-610ab9f5c2bd" xlink:href="nrg-20231231.xsd#nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesTable_17fc7345-bb59-4863-bdec-cc9164371ed7" xlink:href="nrg-20231231.xsd#nrg_ScheduleOfContractAssetsAndLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_25fdef14-4fcf-44c6-b6ec-610ab9f5c2bd" xlink:to="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesTable_17fc7345-bb59-4863-bdec-cc9164371ed7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_1e510731-5b01-4432-b348-400c624bed27" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesTable_17fc7345-bb59-4863-bdec-cc9164371ed7" xlink:to="loc_srt_RangeAxis_1e510731-5b01-4432-b348-400c624bed27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1e510731-5b01-4432-b348-400c624bed27_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_1e510731-5b01-4432-b348-400c624bed27" xlink:to="loc_srt_RangeMember_1e510731-5b01-4432-b348-400c624bed27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_872a880d-48b1-41d5-a81f-9df106b8a151" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_1e510731-5b01-4432-b348-400c624bed27" xlink:to="loc_srt_RangeMember_872a880d-48b1-41d5-a81f-9df106b8a151" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_7d3a57cb-c96b-4df9-ad6f-b4988d0af9b3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_872a880d-48b1-41d5-a81f-9df106b8a151" xlink:to="loc_srt_MinimumMember_7d3a57cb-c96b-4df9-ad6f-b4988d0af9b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_a38e52ea-a568-4c8f-b140-c308ac759a4b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_872a880d-48b1-41d5-a81f-9df106b8a151" xlink:to="loc_srt_MaximumMember_a38e52ea-a568-4c8f-b140-c308ac759a4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_574f8482-6341-46a8-859e-8f64e228807f" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesTable_17fc7345-bb59-4863-bdec-cc9164371ed7" xlink:to="loc_dei_LegalEntityAxis_574f8482-6341-46a8-859e-8f64e228807f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_574f8482-6341-46a8-859e-8f64e228807f_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_574f8482-6341-46a8-859e-8f64e228807f" xlink:to="loc_dei_EntityDomain_574f8482-6341-46a8-859e-8f64e228807f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_6cccf779-3324-4577-b617-58c70bc27997" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_574f8482-6341-46a8-859e-8f64e228807f" xlink:to="loc_dei_EntityDomain_6cccf779-3324-4577-b617-58c70bc27997" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSmartHomeIncMember_cedae2ff-81df-4355-9e92-13de44e52b1e" xlink:href="nrg-20231231.xsd#nrg_VivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_6cccf779-3324-4577-b617-58c70bc27997" xlink:to="loc_nrg_VivintSmartHomeIncMember_cedae2ff-81df-4355-9e92-13de44e52b1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_f4f39dbd-cca2-4b8e-966f-fd15a6d8dbc7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_25fdef14-4fcf-44c6-b6ec-610ab9f5c2bd" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_f4f39dbd-cca2-4b8e-966f-fd15a6d8dbc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ContractWithCustomerTerm_ccd1fa0b-1d77-4702-ba80-42386024ae06" xlink:href="nrg-20231231.xsd#nrg_ContractWithCustomerTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_25fdef14-4fcf-44c6-b6ec-610ab9f5c2bd" xlink:to="loc_nrg_ContractWithCustomerTerm_ccd1fa0b-1d77-4702-ba80-42386024ae06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_5ee69636-6e08-478d-bd45-9a770b09d971" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalizedContractCostAmortizationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleOfContractAssetsAndLiabilitiesLineItems_25fdef14-4fcf-44c6-b6ec-610ab9f5c2bd" xlink:to="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_5ee69636-6e08-478d-bd45-9a770b09d971" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AcquisitionsandDispositionsAcquisitionsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AcquisitionsandDispositionsAcquisitionsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AcquisitionsandDispositionsAcquisitionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_c9f520c9-5ef5-40d6-9eef-00b0e22d0b9a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_c9f520c9-5ef5-40d6-9eef-00b0e22d0b9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c9f520c9-5ef5-40d6-9eef-00b0e22d0b9a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c9f520c9-5ef5-40d6-9eef-00b0e22d0b9a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c9f520c9-5ef5-40d6-9eef-00b0e22d0b9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9de6ad06-6a51-4e87-b1bd-e19be413d3c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_c9f520c9-5ef5-40d6-9eef-00b0e22d0b9a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9de6ad06-6a51-4e87-b1bd-e19be413d3c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintMember_83122530-7cff-47cc-aed4-8a8dad953f6f" xlink:href="nrg-20231231.xsd#nrg_VivintMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9de6ad06-6a51-4e87-b1bd-e19be413d3c9" xlink:to="loc_nrg_VivintMember_83122530-7cff-47cc-aed4-8a8dad953f6f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DirectEnergyMember_3ab2ffe3-c0fd-466c-92e4-7940d296e8f6" xlink:href="nrg-20231231.xsd#nrg_DirectEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9de6ad06-6a51-4e87-b1bd-e19be413d3c9" xlink:to="loc_nrg_DirectEnergyMember_3ab2ffe3-c0fd-466c-92e4-7940d296e8f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_092bd429-3915-4723-8864-9b7baab37957" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:to="loc_us-gaap_DebtInstrumentAxis_092bd429-3915-4723-8864-9b7baab37957" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_092bd429-3915-4723-8864-9b7baab37957_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_092bd429-3915-4723-8864-9b7baab37957" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_092bd429-3915-4723-8864-9b7baab37957_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d20a0722-79f2-484c-87ce-350ef67aa7b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_092bd429-3915-4723-8864-9b7baab37957" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d20a0722-79f2-484c-87ce-350ef67aa7b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A7000SeniorSecuredFirstLienNotesDue2033Member_80835dcd-2763-4059-bc5a-d8faf8d5844f" xlink:href="nrg-20231231.xsd#nrg_A7000SeniorSecuredFirstLienNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_d20a0722-79f2-484c-87ce-350ef67aa7b7" xlink:to="loc_nrg_A7000SeniorSecuredFirstLienNotesDue2033Member_80835dcd-2763-4059-bc5a-d8faf8d5844f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_cbb1d8f7-34ca-49e1-a073-63df71bf0cc3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_cbb1d8f7-34ca-49e1-a073-63df71bf0cc3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_cbb1d8f7-34ca-49e1-a073-63df71bf0cc3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_cbb1d8f7-34ca-49e1-a073-63df71bf0cc3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_cbb1d8f7-34ca-49e1-a073-63df71bf0cc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_9079dc77-012a-4460-914e-e51261f868b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_cbb1d8f7-34ca-49e1-a073-63df71bf0cc3" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_9079dc77-012a-4460-914e-e51261f868b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_a7f067b2-cf6d-4d14-b4be-0731f1f3cd0a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9079dc77-012a-4460-914e-e51261f868b4" xlink:to="loc_us-gaap_SeniorNotesMember_a7f067b2-cf6d-4d14-b4be-0731f1f3cd0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_065be514-f154-4e4d-81bb-12f6321f44fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:to="loc_us-gaap_StatementClassOfStockAxis_065be514-f154-4e4d-81bb-12f6321f44fc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_065be514-f154-4e4d-81bb-12f6321f44fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_065be514-f154-4e4d-81bb-12f6321f44fc" xlink:to="loc_us-gaap_ClassOfStockDomain_065be514-f154-4e4d-81bb-12f6321f44fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_92553e57-7ad2-462f-b82f-a46706a3f4b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_065be514-f154-4e4d-81bb-12f6321f44fc" xlink:to="loc_us-gaap_ClassOfStockDomain_92553e57-7ad2-462f-b82f-a46706a3f4b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_782d7435-0638-432f-974d-5ec43356fc38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_92553e57-7ad2-462f-b82f-a46706a3f4b9" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_782d7435-0638-432f-974d-5ec43356fc38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_f321f9f9-2910-4598-a0ac-6982dd8b2f1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:to="loc_us-gaap_CreditFacilityAxis_f321f9f9-2910-4598-a0ac-6982dd8b2f1e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_f321f9f9-2910-4598-a0ac-6982dd8b2f1e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_f321f9f9-2910-4598-a0ac-6982dd8b2f1e" xlink:to="loc_us-gaap_CreditFacilityDomain_f321f9f9-2910-4598-a0ac-6982dd8b2f1e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_4ada863a-543f-4444-892a-0dd5f22e81ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_f321f9f9-2910-4598-a0ac-6982dd8b2f1e" xlink:to="loc_us-gaap_CreditFacilityDomain_4ada863a-543f-4444-892a-0dd5f22e81ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_8b95b699-5f79-4142-bcc3-d0e5d40539d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4ada863a-543f-4444-892a-0dd5f22e81ba" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_8b95b699-5f79-4142-bcc3-d0e5d40539d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b18c672b-ad52-4acf-8c42-64d5226e41a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b18c672b-ad52-4acf-8c42-64d5226e41a9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b18c672b-ad52-4acf-8c42-64d5226e41a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b18c672b-ad52-4acf-8c42-64d5226e41a9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b18c672b-ad52-4acf-8c42-64d5226e41a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b7c548df-9248-414f-bbc9-ec713accc550" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b18c672b-ad52-4acf-8c42-64d5226e41a9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b7c548df-9248-414f-bbc9-ec713accc550" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_bcd45461-2b4f-4eb4-8018-d3e9ac0b07cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b7c548df-9248-414f-bbc9-ec713accc550" xlink:to="loc_us-gaap_CustomerRelationshipsMember_bcd45461-2b4f-4eb4-8018-d3e9ac0b07cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_7792a5ef-f6bf-4b11-94c8-b20903207fc8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b7c548df-9248-414f-bbc9-ec713accc550" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_7792a5ef-f6bf-4b11-94c8-b20903207fc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_4a5385f1-e961-4a34-9cac-0ee89c93917d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b7c548df-9248-414f-bbc9-ec713accc550" xlink:to="loc_us-gaap_TradeNamesMember_4a5385f1-e961-4a34-9cac-0ee89c93917d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_971becb2-982f-4ac8-a664-b1754bc8d620" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_7efb6c49-883a-4596-b467-7755d8144b9a" xlink:to="loc_srt_StatementGeographicalAxis_971becb2-982f-4ac8-a664-b1754bc8d620" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_971becb2-982f-4ac8-a664-b1754bc8d620_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_971becb2-982f-4ac8-a664-b1754bc8d620" xlink:to="loc_srt_SegmentGeographicalDomain_971becb2-982f-4ac8-a664-b1754bc8d620_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_38cc18e8-9934-4c25-9511-6478eac1182f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_971becb2-982f-4ac8-a664-b1754bc8d620" xlink:to="loc_srt_SegmentGeographicalDomain_38cc18e8-9934-4c25-9511-6478eac1182f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_3c877824-55bd-4259-b77e-2c3732cec962" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_38cc18e8-9934-4c25-9511-6478eac1182f" xlink:to="loc_country_US_3c877824-55bd-4259-b77e-2c3732cec962" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_03383131-532e-46f2-a5b9-42cb9cebbf2e" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_38cc18e8-9934-4c25-9511-6478eac1182f" xlink:to="loc_country_CA_03383131-532e-46f2-a5b9-42cb9cebbf2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfCustomers_af0fed65-8dc7-4714-9864-ae1f006392c3" xlink:href="nrg-20231231.xsd#nrg_NumberOfCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_nrg_NumberOfCustomers_af0fed65-8dc7-4714-9864-ae1f006392c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_559812cf-509c-4303-9d39-6498a8e2e0e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_559812cf-509c-4303-9d39-6498a8e2e0e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_6fc20751-1038-41c0-96fd-737423d8351a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_6fc20751-1038-41c0-96fd-737423d8351a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_302f12af-d940-4d71-96e3-bcf75738cacc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_302f12af-d940-4d71-96e3-bcf75738cacc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_b20ec6b0-6ab4-4039-a7ef-78d28fca45e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_b20ec6b0-6ab4-4039-a7ef-78d28fca45e6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_707ca6ba-682d-4075-8e09-32956f825d53" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_707ca6ba-682d-4075-8e09-32956f825d53" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_42519cdc-0f9f-4cca-9218-739bc7e335ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_42519cdc-0f9f-4cca-9218-739bc7e335ca" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_d5a3d158-52d4-48ae-ac6c-8c05dacd3a3a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_d5a3d158-52d4-48ae-ac6c-8c05dacd3a3a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_9129bfaf-1122-4a3c-9a35-3ebef27f2751" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_9129bfaf-1122-4a3c-9a35-3ebef27f2751" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_79633d40-7857-443c-aadc-70aef0c35bc8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_79633d40-7857-443c-aadc-70aef0c35bc8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity_73c135ca-3f03-4cf5-a6ba-66b07e24c26b" xlink:href="nrg-20231231.xsd#nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity_73c135ca-3f03-4cf5-a6ba-66b07e24c26b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_1ddb3c0a-9796-42a4-800c-0004b3e5bd4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_1ddb3c0a-9796-42a4-800c-0004b3e5bd4f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_59280f42-5f4d-4512-96fc-a2770ddb6b58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_59280f42-5f4d-4512-96fc-a2770ddb6b58" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_fde14e99-14fc-444b-a35f-01c01ca208ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_fde14e99-14fc-444b-a35f-01c01ca208ba" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt_e5d26dce-7db8-4be3-ae39-06bf7a6f6c8f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebt_e5d26dce-7db8-4be3-ae39-06bf7a6f6c8f" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AmortizationOfDifferenceBetweenPrincipalAndFairValueOfAcquiredDebtOverRemainingTerm_dfc8f805-bb40-4029-a046-50b0bddf1923" xlink:href="nrg-20231231.xsd#nrg_AmortizationOfDifferenceBetweenPrincipalAndFairValueOfAcquiredDebtOverRemainingTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_nrg_AmortizationOfDifferenceBetweenPrincipalAndFairValueOfAcquiredDebtOverRemainingTerm_dfc8f805-bb40-4029-a046-50b0bddf1923" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfStatesInWhichEntityOperates_de1fa823-243a-4cff-a874-04bb9420c562" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfStatesInWhichEntityOperates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_NumberOfStatesInWhichEntityOperates_de1fa823-243a-4cff-a874-04bb9420c562" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfProvincesInWhichEntityOperates_b19b5e38-1657-483b-9f89-65922db2db47" xlink:href="nrg-20231231.xsd#nrg_NumberOfProvincesInWhichEntityOperates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_nrg_NumberOfProvincesInWhichEntityOperates_b19b5e38-1657-483b-9f89-65922db2db47" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_85685d2b-00f9-4d68-894e-cf4cbdc24d7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_85685d2b-00f9-4d68-894e-cf4cbdc24d7d" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_8a104ae1-5617-4f73-8333-1b99a8aea5b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fd423c51-2a64-401a-8a84-ba76fce00616" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_8a104ae1-5617-4f73-8333-1b99a8aea5b0" xlink:type="arc" order="19"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AcquisitionsandDispositionsConsiderationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AcquisitionsandDispositionsConsiderationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AcquisitionsandDispositionsConsiderationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_fecc03f8-d34a-4e23-bd19-a423981ba193" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_fecc03f8-d34a-4e23-bd19-a423981ba193" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_5e8912e9-4897-46bf-86b5-23e76da85dc4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_fecc03f8-d34a-4e23-bd19-a423981ba193" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_5e8912e9-4897-46bf-86b5-23e76da85dc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5e8912e9-4897-46bf-86b5-23e76da85dc4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5e8912e9-4897-46bf-86b5-23e76da85dc4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5e8912e9-4897-46bf-86b5-23e76da85dc4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_132ab90d-65ab-45f6-b77c-b807705e2ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5e8912e9-4897-46bf-86b5-23e76da85dc4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_132ab90d-65ab-45f6-b77c-b807705e2ccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintMember_3797ec2f-4c3d-4049-b7b8-f995ae052e36" xlink:href="nrg-20231231.xsd#nrg_VivintMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_132ab90d-65ab-45f6-b77c-b807705e2ccd" xlink:to="loc_nrg_VivintMember_3797ec2f-4c3d-4049-b7b8-f995ae052e36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_21db1820-efea-44d5-a806-4428f8ef149d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityInterestIssuedOrIssuableByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_fecc03f8-d34a-4e23-bd19-a423981ba193" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_21db1820-efea-44d5-a806-4428f8ef149d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_21db1820-efea-44d5-a806-4428f8ef149d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_21db1820-efea-44d5-a806-4428f8ef149d" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_21db1820-efea-44d5-a806-4428f8ef149d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_5f41cc85-13fb-42e1-861c-3b62e0f34c4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityInterestIssuedOrIssuableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableByTypeAxis_21db1820-efea-44d5-a806-4428f8ef149d" xlink:to="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_5f41cc85-13fb-42e1-861c-3b62e0f34c4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EquityAwardsPreCombinationServiceMember_d698f3d8-6061-4197-8c81-d29cb6b8d463" xlink:href="nrg-20231231.xsd#nrg_EquityAwardsPreCombinationServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityInterestIssuedOrIssuableTypeDomain_5f41cc85-13fb-42e1-861c-3b62e0f34c4e" xlink:to="loc_nrg_EquityAwardsPreCombinationServiceMember_d698f3d8-6061-4197-8c81-d29cb6b8d463" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessAcquisitionSharesOutstanding_3bfc2c95-6ac5-4adc-864b-371971d7593c" xlink:href="nrg-20231231.xsd#nrg_BusinessAcquisitionSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_nrg_BusinessAcquisitionSharesOutstanding_3bfc2c95-6ac5-4adc-864b-371971d7593c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_95175c45-14e5-4e2b-817c-6e6443a259a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_95175c45-14e5-4e2b-817c-6e6443a259a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PaymentsToAcquireBusinessesEquityInterestInAcquireeOutstandingShares_1a51868a-3006-468d-8905-3c0f46c8a916" xlink:href="nrg-20231231.xsd#nrg_PaymentsToAcquireBusinessesEquityInterestInAcquireeOutstandingShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_nrg_PaymentsToAcquireBusinessesEquityInterestInAcquireeOutstandingShares_1a51868a-3006-468d-8905-3c0f46c8a916" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PaymentsToAcquireBusinessesAcquireeOtherEquityInstrumentsCashOutShareBasedPaymentArrangementsStockAppreciationRightsAndPrivatePlacementWarrants_71850270-7f1a-4a43-8d2b-40bfccb4293b" xlink:href="nrg-20231231.xsd#nrg_PaymentsToAcquireBusinessesAcquireeOtherEquityInstrumentsCashOutShareBasedPaymentArrangementsStockAppreciationRightsAndPrivatePlacementWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_nrg_PaymentsToAcquireBusinessesAcquireeOtherEquityInstrumentsCashOutShareBasedPaymentArrangementsStockAppreciationRightsAndPrivatePlacementWarrants_71850270-7f1a-4a43-8d2b-40bfccb4293b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_8ffc5b07-d4af-4c31-ad10-5ea1f29717a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_8ffc5b07-d4af-4c31-ad10-5ea1f29717a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_1b2a7557-dd05-4f7d-a256-4127b3d41131" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_1b2a7557-dd05-4f7d-a256-4127b3d41131" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_ae2f51ce-6cbb-4190-9d3f-ecb0da1e20b3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d031897f-24f1-45e0-b85d-161e414f09b7" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_ae2f51ce-6cbb-4190-9d3f-ecb0da1e20b3" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AcquisitionsandDispositionsVivintPurchasePriceAllocationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AcquisitionsandDispositionsVivintPurchasePriceAllocationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AcquisitionsandDispositionsVivintPurchasePriceAllocationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4293d477-3753-4c9e-bc25-16ca121c3734" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4293d477-3753-4c9e-bc25-16ca121c3734" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_5fadaa92-3c88-412d-a5fd-0f99a89f2af2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4293d477-3753-4c9e-bc25-16ca121c3734" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_5fadaa92-3c88-412d-a5fd-0f99a89f2af2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5fadaa92-3c88-412d-a5fd-0f99a89f2af2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5fadaa92-3c88-412d-a5fd-0f99a89f2af2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5fadaa92-3c88-412d-a5fd-0f99a89f2af2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9bd99d5e-348d-409e-9747-c12601c73cb9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5fadaa92-3c88-412d-a5fd-0f99a89f2af2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9bd99d5e-348d-409e-9747-c12601c73cb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintMember_29a47659-e7f4-4b3e-b5e8-5ec1eb02c36a" xlink:href="nrg-20231231.xsd#nrg_VivintMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9bd99d5e-348d-409e-9747-c12601c73cb9" xlink:to="loc_nrg_VivintMember_29a47659-e7f4-4b3e-b5e8-5ec1eb02c36a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2ddbe111-2432-49ef-bb55-5813ca9d225f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4293d477-3753-4c9e-bc25-16ca121c3734" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2ddbe111-2432-49ef-bb55-5813ca9d225f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ddbe111-2432-49ef-bb55-5813ca9d225f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2ddbe111-2432-49ef-bb55-5813ca9d225f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ddbe111-2432-49ef-bb55-5813ca9d225f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_053b0b94-9522-4ecc-86aa-55fc4ce2306c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2ddbe111-2432-49ef-bb55-5813ca9d225f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_053b0b94-9522-4ecc-86aa-55fc4ce2306c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_478f6d69-4498-4738-926b-ef8bfc4ccb5f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_053b0b94-9522-4ecc-86aa-55fc4ce2306c" xlink:to="loc_us-gaap_CustomerRelationshipsMember_478f6d69-4498-4738-926b-ef8bfc4ccb5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_d7999af2-7d88-49a0-a4fe-1b4457719f71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_053b0b94-9522-4ecc-86aa-55fc4ce2306c" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_d7999af2-7d88-49a0-a4fe-1b4457719f71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_8cc9d503-2ee7-4ded-824f-75954fc041fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_053b0b94-9522-4ecc-86aa-55fc4ce2306c" xlink:to="loc_us-gaap_TradeNamesMember_8cc9d503-2ee7-4ded-824f-75954fc041fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SalesChannelContractsBasedIntangibleAssetsMember_7ab94c0c-d3b3-4a7b-a6a6-3ef4f14be221" xlink:href="nrg-20231231.xsd#nrg_SalesChannelContractsBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_053b0b94-9522-4ecc-86aa-55fc4ce2306c" xlink:to="loc_nrg_SalesChannelContractsBasedIntangibleAssetsMember_7ab94c0c-d3b3-4a7b-a6a6-3ef4f14be221" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_d7248cfc-f82a-4720-a5dc-ff1a17fcd83b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_d7248cfc-f82a-4720-a5dc-ff1a17fcd83b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_021e01ce-8fef-4f18-98d3-794c8fd06773" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_d7248cfc-f82a-4720-a5dc-ff1a17fcd83b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_021e01ce-8fef-4f18-98d3-794c8fd06773" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_ef025a2c-c9c8-404d-9eb6-6c1df426e9b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_d7248cfc-f82a-4720-a5dc-ff1a17fcd83b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_ef025a2c-c9c8-404d-9eb6-6c1df426e9b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_a81951d4-6718-4cb8-b5ac-39c71f4ee5b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_d7248cfc-f82a-4720-a5dc-ff1a17fcd83b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_a81951d4-6718-4cb8-b5ac-39c71f4ee5b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_5f577b36-8301-4906-b350-9bef30b41c3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_d7248cfc-f82a-4720-a5dc-ff1a17fcd83b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_5f577b36-8301-4906-b350-9bef30b41c3f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_5ab6cb32-36da-41ba-9cf6-8eac6bc862ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_d7248cfc-f82a-4720-a5dc-ff1a17fcd83b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_5ab6cb32-36da-41ba-9cf6-8eac6bc862ef" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_941a1e90-36ae-4d14-99f1-29239a236552" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_941a1e90-36ae-4d14-99f1-29239a236552" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsOperatingLeaseRightOfUseAssetsNet_08759e64-38b4-460c-ad38-091f61ec91a1" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsOperatingLeaseRightOfUseAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsOperatingLeaseRightOfUseAssetsNet_08759e64-38b4-460c-ad38-091f61ec91a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_f909f9b4-8ed0-4231-9b0d-d1f7b8e1c65d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:to="loc_us-gaap_Goodwill_f909f9b4-8ed0-4231-9b0d-d1f7b8e1c65d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_9f664628-8868-4c71-a5a0-1a571e1b71c8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_9f664628-8868-4c71-a5a0-1a571e1b71c8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets_d89f961f-c4d3-45bd-8466-07ea526137ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets_d89f961f-c4d3-45bd-8466-07ea526137ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_55df472e-5070-4a9d-b61b-0e9d4fa72faa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_55df472e-5070-4a9d-b61b-0e9d4fa72faa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsIncludingGoodwill_78584bc5-6148-42be-88b7-341dbb899214" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_3b0d8b2d-f19f-4a8b-95fc-ff27c9d3876f" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsIncludingGoodwill_78584bc5-6148-42be-88b7-341dbb899214" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_47a223fa-b439-453a-b1d1-c5a2a357e71c" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_47a223fa-b439-453a-b1d1-c5a2a357e71c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebtAndFinanceLeaseObligations_29d385e1-ba06-4701-9972-6d0ff01ec88b" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebtAndFinanceLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesLongTermDebtAndFinanceLeaseObligations_29d385e1-ba06-4701-9972-6d0ff01ec88b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOperatingLeaseLiabilities_8acdfb39-9d5d-4b37-8dd1-f3cb7eb8439f" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOperatingLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOperatingLeaseLiabilities_8acdfb39-9d5d-4b37-8dd1-f3cb7eb8439f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_736f7681-bc77-45d1-b572-dfd3083b223d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_736f7681-bc77-45d1-b572-dfd3083b223d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDerivativeLiabilities_5bc769d3-59ae-4121-9c07-edf8ce799f25" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDerivativeLiabilities_5bc769d3-59ae-4121-9c07-edf8ce799f25" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_5c681abe-2be9-4d7f-8502-30eaf91d9b7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_5c681abe-2be9-4d7f-8502-30eaf91d9b7d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherCurrentLiabilities_57acc698-19f7-49d9-a584-90b72193cd26" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherCurrentLiabilities_57acc698-19f7-49d9-a584-90b72193cd26" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_7c8dcc5a-a786-481d-85ac-d341d0235428" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_287521db-fdbd-491c-879b-ee956998d6fa" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_7c8dcc5a-a786-481d-85ac-d341d0235428" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebtAndFinanceLeaseObligations_656fe013-76c5-4555-8c16-3d0377a09ead" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebtAndFinanceLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebtAndFinanceLeaseObligations_656fe013-76c5-4555-8c16-3d0377a09ead" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOperatingLeaseLiabilities_da313e43-d625-4273-ae7f-6a8c3c4c6eac" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOperatingLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOperatingLeaseLiabilities_da313e43-d625-4273-ae7f-6a8c3c4c6eac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesDerivativeLiabilities_2bf769d7-2963-41d5-a6e1-1e12e7c698b6" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesDerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesDerivativeLiabilities_2bf769d7-2963-41d5-a6e1-1e12e7c698b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_157e518c-a04d-4d4c-9b61-9e8933901fa7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_157e518c-a04d-4d4c-9b61-9e8933901fa7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesDeferredRevenueNoncurrent_1c009086-7a5b-4ccb-b9d9-439b79d006b3" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesDeferredRevenueNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:to="loc_nrg_BusinessCombinationBusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesDeferredRevenueNoncurrent_1c009086-7a5b-4ccb-b9d9-439b79d006b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_7694cd69-6ac3-463c-a3af-394d58dbafed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_7694cd69-6ac3-463c-a3af-394d58dbafed" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities_5891a99e-716d-49a6-b990-73036a98cc5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_98feeeae-d82e-4700-87e5-28b8574fa78d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities_5891a99e-716d-49a6-b990-73036a98cc5c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_151ff70b-e846-47da-bf31-6e07528d4492" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_151ff70b-e846-47da-bf31-6e07528d4492" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_7cc46c10-351c-41b8-a411-9b506c827412" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_7cc46c10-351c-41b8-a411-9b506c827412" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_fa0675e7-73f9-46d1-b841-54ec9a1c527e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_fa0675e7-73f9-46d1-b841-54ec9a1c527e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_647cb38e-52bd-4a37-bd15-789b22af066f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_8ff7db51-866c-45ba-bd4e-ca729b18f784" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_647cb38e-52bd-4a37-bd15-789b22af066f" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AcquisitionsandDispositionsSupplementalProFormaFinancialInformationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AcquisitionsandDispositionsSupplementalProFormaFinancialInformationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AcquisitionsandDispositionsSupplementalProFormaFinancialInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_50d3b440-7dff-4d82-bbbc-d21f20e8ca1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_55ecdcf7-8df2-4252-bebd-7093604b0171" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_50d3b440-7dff-4d82-bbbc-d21f20e8ca1a" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_55ecdcf7-8df2-4252-bebd-7093604b0171" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_75199111-5b0c-41fb-b98a-77db0a6defe0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_55ecdcf7-8df2-4252-bebd-7093604b0171" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_75199111-5b0c-41fb-b98a-77db0a6defe0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_75199111-5b0c-41fb-b98a-77db0a6defe0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_75199111-5b0c-41fb-b98a-77db0a6defe0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_75199111-5b0c-41fb-b98a-77db0a6defe0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3f638d95-d4c6-4cfb-b76c-a42e7ba7bb2a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_75199111-5b0c-41fb-b98a-77db0a6defe0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3f638d95-d4c6-4cfb-b76c-a42e7ba7bb2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintMember_aaa202a2-6905-4b01-93c6-ea05f4d8d971" xlink:href="nrg-20231231.xsd#nrg_VivintMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3f638d95-d4c6-4cfb-b76c-a42e7ba7bb2a" xlink:to="loc_nrg_VivintMember_aaa202a2-6905-4b01-93c6-ea05f4d8d971" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_7522532b-2907-4023-aef7-a45084951ae7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_50d3b440-7dff-4d82-bbbc-d21f20e8ca1a" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_7522532b-2907-4023-aef7-a45084951ae7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_820f22b6-46b0-4b23-9faf-6c4ebc355410" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_50d3b440-7dff-4d82-bbbc-d21f20e8ca1a" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_820f22b6-46b0-4b23-9faf-6c4ebc355410" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AcquisitionsandDispositionsDirectEnergyPurchasePriceAllocationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AcquisitionsandDispositionsDirectEnergyPurchasePriceAllocationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AcquisitionsandDispositionsDirectEnergyPurchasePriceAllocationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ffd489c3-7ace-4e23-8295-8f567aa8c5f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ffd489c3-7ace-4e23-8295-8f567aa8c5f9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_2fdf510b-f47c-48e0-b93a-79b9ca971f03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ffd489c3-7ace-4e23-8295-8f567aa8c5f9" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_2fdf510b-f47c-48e0-b93a-79b9ca971f03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2fdf510b-f47c-48e0-b93a-79b9ca971f03_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2fdf510b-f47c-48e0-b93a-79b9ca971f03" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2fdf510b-f47c-48e0-b93a-79b9ca971f03_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3034b664-8760-47b1-83af-2904250e4e5f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2fdf510b-f47c-48e0-b93a-79b9ca971f03" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3034b664-8760-47b1-83af-2904250e4e5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DirectEnergyMember_38445f1d-446b-4919-bfcd-91533c69def4" xlink:href="nrg-20231231.xsd#nrg_DirectEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3034b664-8760-47b1-83af-2904250e4e5f" xlink:to="loc_nrg_DirectEnergyMember_38445f1d-446b-4919-bfcd-91533c69def4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b584edd0-f862-4a4c-9779-dbe779cbb3e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ffd489c3-7ace-4e23-8295-8f567aa8c5f9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b584edd0-f862-4a4c-9779-dbe779cbb3e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b584edd0-f862-4a4c-9779-dbe779cbb3e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b584edd0-f862-4a4c-9779-dbe779cbb3e4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b584edd0-f862-4a4c-9779-dbe779cbb3e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7c8ed26f-c307-472c-965f-f42bb2ad0916" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b584edd0-f862-4a4c-9779-dbe779cbb3e4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7c8ed26f-c307-472c-965f-f42bb2ad0916" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_24894ae7-5c3d-4b9b-bec4-b05b97af77bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7c8ed26f-c307-472c-965f-f42bb2ad0916" xlink:to="loc_us-gaap_CustomerRelationshipsMember_24894ae7-5c3d-4b9b-bec4-b05b97af77bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CustomerAndSupplyContractsMember_f5b6986a-369f-4db2-92f7-e0a152d5221f" xlink:href="nrg-20231231.xsd#nrg_CustomerAndSupplyContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7c8ed26f-c307-472c-965f-f42bb2ad0916" xlink:to="loc_nrg_CustomerAndSupplyContractsMember_f5b6986a-369f-4db2-92f7-e0a152d5221f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_be8082de-23ec-4efb-b85b-68b2797a75a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7c8ed26f-c307-472c-965f-f42bb2ad0916" xlink:to="loc_us-gaap_TradeNamesMember_be8082de-23ec-4efb-b85b-68b2797a75a0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RenewableEnergyCertificatesMember_e6331707-8b68-48da-9e3f-4d806d6724ed" xlink:href="nrg-20231231.xsd#nrg_RenewableEnergyCertificatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7c8ed26f-c307-472c-965f-f42bb2ad0916" xlink:to="loc_nrg_RenewableEnergyCertificatesMember_e6331707-8b68-48da-9e3f-4d806d6724ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_e43ddda7-e9b0-4916-8a96-f740fa45766e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ffd489c3-7ace-4e23-8295-8f567aa8c5f9" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_e43ddda7-e9b0-4916-8a96-f740fa45766e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e43ddda7-e9b0-4916-8a96-f740fa45766e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e43ddda7-e9b0-4916-8a96-f740fa45766e" xlink:to="loc_us-gaap_SegmentDomain_e43ddda7-e9b0-4916-8a96-f740fa45766e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_aacc1698-4d5b-4f05-a06b-f2810d0d3b37" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e43ddda7-e9b0-4916-8a96-f740fa45766e" xlink:to="loc_us-gaap_SegmentDomain_aacc1698-4d5b-4f05-a06b-f2810d0d3b37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TexasSegmentMember_4ff8432e-7437-49e9-9571-ad0038cf6e72" xlink:href="nrg-20231231.xsd#nrg_TexasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_aacc1698-4d5b-4f05-a06b-f2810d0d3b37" xlink:to="loc_nrg_TexasSegmentMember_4ff8432e-7437-49e9-9571-ad0038cf6e72" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EastSegmentMember_df14cd12-5df5-4206-ab26-e213dacb2cb5" xlink:href="nrg-20231231.xsd#nrg_EastSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_aacc1698-4d5b-4f05-a06b-f2810d0d3b37" xlink:to="loc_nrg_EastSegmentMember_df14cd12-5df5-4206-ab26-e213dacb2cb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WestServicesAndOtherSegmentMember_8f500a9a-538e-4403-b4f4-8b82a706a2ca" xlink:href="nrg-20231231.xsd#nrg_WestServicesAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_aacc1698-4d5b-4f05-a06b-f2810d0d3b37" xlink:to="loc_nrg_WestServicesAndOtherSegmentMember_8f500a9a-538e-4403-b4f4-8b82a706a2ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_cc61d9e9-0f0f-43f9-a974-0b93422ce380" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_cc61d9e9-0f0f-43f9-a974-0b93422ce380" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFundsDepositedByCounterparties_9a6faa50-20c9-4162-b9e0-1b5a0c6356a1" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFundsDepositedByCounterparties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFundsDepositedByCounterparties_9a6faa50-20c9-4162-b9e0-1b5a0c6356a1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRestrictedCash_3898a0f4-e672-40a1-9eb1-1a5a45aeda2b" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedRestrictedCash_3898a0f4-e672-40a1-9eb1-1a5a45aeda2b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_bd7fbe50-c00f-4187-9581-98855addf9c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_bd7fbe50-c00f-4187-9581-98855addf9c9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_b932cb31-737e-4d37-979a-7b3aae6d3498" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_b932cb31-737e-4d37-979a-7b3aae6d3498" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeAssetsCurrent_de36ea4f-885d-440d-a738-699a644310dd" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeAssetsCurrent_de36ea4f-885d-440d-a738-699a644310dd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsCashCollateralDeposits_7c0837a1-30bf-475d-b048-4aabda8f6c88" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsCashCollateralDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsCashCollateralDeposits_7c0837a1-30bf-475d-b048-4aabda8f6c88" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_daa03f3b-08b3-410c-8f98-814f0b810785" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_daa03f3b-08b3-410c-8f98-814f0b810785" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_36c15b3d-004a-40c7-afcd-7d64ef0cebda" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAbstract_f01879d7-1fc2-4995-a32b-28cc2f7f22ee" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssets_36c15b3d-004a-40c7-afcd-7d64ef0cebda" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_38ba9688-e1b1-4c8b-8d07-64bbed28cb41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_38ba9688-e1b1-4c8b-8d07-64bbed28cb41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_c43198b3-91c2-4b6d-b8b1-66fbf6e9bf3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_c43198b3-91c2-4b6d-b8b1-66fbf6e9bf3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_bb213464-d24f-4f4e-819e-f83f58a14f36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_c43198b3-91c2-4b6d-b8b1-66fbf6e9bf3e" xlink:to="loc_us-gaap_Goodwill_bb213464-d24f-4f4e-819e-f83f58a14f36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_5288c9a3-e58d-4c3d-8d3a-1a86b34ea5d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_c43198b3-91c2-4b6d-b8b1-66fbf6e9bf3e" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_5288c9a3-e58d-4c3d-8d3a-1a86b34ea5d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeAssetsNoncurrent_c3e0a4fb-32a9-48a1-a5d1-c8cc15777add" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_c43198b3-91c2-4b6d-b8b1-66fbf6e9bf3e" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeAssetsNoncurrent_c3e0a4fb-32a9-48a1-a5d1-c8cc15777add" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_f2baf0a0-ea6f-4c21-864b-d16b2f3d8bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_c43198b3-91c2-4b6d-b8b1-66fbf6e9bf3e" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_f2baf0a0-ea6f-4c21-864b-d16b2f3d8bf5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsIncludingGoodwill_dd6dbaf4-a071-4339-8b7d-256790a7f7c5" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsAbstract_c43198b3-91c2-4b6d-b8b1-66fbf6e9bf3e" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentAssetsIncludingGoodwill_dd6dbaf4-a071-4339-8b7d-256790a7f7c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_cee452bb-6367-44a7-bc02-f33c67de51c1" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_cee452bb-6367-44a7-bc02-f33c67de51c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_b7e267c2-71a9-4950-becf-a204906c3262" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_b7e267c2-71a9-4950-becf-a204906c3262" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_cc89443c-950f-4314-9b87-ac81bccff352" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_b7e267c2-71a9-4950-becf-a204906c3262" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_cc89443c-950f-4314-9b87-ac81bccff352" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeLiabilityCurrent_ddbf0aba-d5e8-4ba2-a625-14886a75c39d" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_b7e267c2-71a9-4950-becf-a204906c3262" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeLiabilityCurrent_ddbf0aba-d5e8-4ba2-a625-14886a75c39d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesCollateralFundsDepositsReceived_43816ff9-3d16-4d91-b63a-b900d8c398c4" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesCollateralFundsDepositsReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_b7e267c2-71a9-4950-becf-a204906c3262" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesCollateralFundsDepositsReceived_43816ff9-3d16-4d91-b63a-b900d8c398c4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherCurrentLiabilities_64da2d46-466a-4326-8336-d99850b994f3" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_b7e267c2-71a9-4950-becf-a204906c3262" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherCurrentLiabilities_64da2d46-466a-4326-8336-d99850b994f3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_e3cb6ea2-9c0d-4f83-b496-179fd8d7714e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAbstract_b7e267c2-71a9-4950-becf-a204906c3262" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilities_e3cb6ea2-9c0d-4f83-b496-179fd8d7714e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_31a98327-3a77-47d4-bd4f-4b40fd273d62" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_31a98327-3a77-47d4-bd4f-4b40fd273d62" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeLiabilityNoncurrent_9157f956-070a-4769-a6c6-36dbead583e4" xlink:href="nrg-20231231.xsd#nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_31a98327-3a77-47d4-bd4f-4b40fd273d62" xlink:to="loc_nrg_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDerivativeLiabilityNoncurrent_9157f956-070a-4769-a6c6-36dbead583e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_c4dea78e-050a-45ce-acd7-42ad09309020" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_31a98327-3a77-47d4-bd4f-4b40fd273d62" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_c4dea78e-050a-45ce-acd7-42ad09309020" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_b7b33245-c70d-4ed0-bb10-a51b302ec8ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_31a98327-3a77-47d4-bd4f-4b40fd273d62" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_b7b33245-c70d-4ed0-bb10-a51b302ec8ea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities_5dbec643-147c-4883-850b-b70e16dcc5d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAbstract_31a98327-3a77-47d4-bd4f-4b40fd273d62" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilities_5dbec643-147c-4883-850b-b70e16dcc5d4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_2aa33bc0-5fde-4ac1-b45e-90a0d4134d31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_2aa33bc0-5fde-4ac1-b45e-90a0d4134d31" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_e6a087a5-7d05-4bcc-b865-fdf9e0b4fea1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_e6a087a5-7d05-4bcc-b865-fdf9e0b4fea1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_f6852756-6057-47e9-b3b9-6e6f5b758300" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_f6852756-6057-47e9-b3b9-6e6f5b758300" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_f5975578-afc6-4872-ba94-c305a088dc97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a218e6ea-4cbd-470e-a338-8d43e39dcfe7" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_f5975578-afc6-4872-ba94-c305a088dc97" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AcquisitionsandDispositionsDispositionsNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AcquisitionsandDispositionsDispositionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AcquisitionsandDispositionsDispositionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2183437a-6f9b-4cbd-aa6a-7be2b65b7b0c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2183437a-6f9b-4cbd-aa6a-7be2b65b7b0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_2183437a-6f9b-4cbd-aa6a-7be2b65b7b0c_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2183437a-6f9b-4cbd-aa6a-7be2b65b7b0c" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_2183437a-6f9b-4cbd-aa6a-7be2b65b7b0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_17be59f2-de5e-4c47-9843-1d5079ac1ffc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_2183437a-6f9b-4cbd-aa6a-7be2b65b7b0c" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_17be59f2-de5e-4c47-9843-1d5079ac1ffc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_26224751-acc4-4151-ab5b-f42c961e48d1" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_17be59f2-de5e-4c47-9843-1d5079ac1ffc" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_26224751-acc4-4151-ab5b-f42c961e48d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WatsonFacilityMember_7f4ac1bb-4754-495a-a702-21a493d3eb50" xlink:href="nrg-20231231.xsd#nrg_WatsonFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_17be59f2-de5e-4c47-9843-1d5079ac1ffc" xlink:to="loc_nrg_WatsonFacilityMember_7f4ac1bb-4754-495a-a702-21a493d3eb50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ArthurKillPlantMember_5df34859-e75a-4215-b20e-78a78c290acc" xlink:href="nrg-20231231.xsd#nrg_ArthurKillPlantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_17be59f2-de5e-4c47-9843-1d5079ac1ffc" xlink:to="loc_nrg_ArthurKillPlantMember_5df34859-e75a-4215-b20e-78a78c290acc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8a8e2424-a0bd-41cc-9e73-5aef9e05323c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8a8e2424-a0bd-41cc-9e73-5aef9e05323c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8a8e2424-a0bd-41cc-9e73-5aef9e05323c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8a8e2424-a0bd-41cc-9e73-5aef9e05323c" xlink:to="loc_us-gaap_SegmentDomain_8a8e2424-a0bd-41cc-9e73-5aef9e05323c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a014e935-f579-4fa7-9059-ae3287be44c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8a8e2424-a0bd-41cc-9e73-5aef9e05323c" xlink:to="loc_us-gaap_SegmentDomain_a014e935-f579-4fa7-9059-ae3287be44c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EastSegmentMember_95c072d7-d021-4c3f-811e-0ab85c859213" xlink:href="nrg-20231231.xsd#nrg_EastSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a014e935-f579-4fa7-9059-ae3287be44c0" xlink:to="loc_nrg_EastSegmentMember_95c072d7-d021-4c3f-811e-0ab85c859213" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EastAndWestMember_970aa716-27ea-4e00-9943-85de3550335d" xlink:href="nrg-20231231.xsd#nrg_EastAndWestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a014e935-f579-4fa7-9059-ae3287be44c0" xlink:to="loc_nrg_EastAndWestMember_970aa716-27ea-4e00-9943-85de3550335d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_3413ab18-18c0-4aa2-a079-d2f9bb3dd7da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_3413ab18-18c0-4aa2-a079-d2f9bb3dd7da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_3413ab18-18c0-4aa2-a079-d2f9bb3dd7da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_3413ab18-18c0-4aa2-a079-d2f9bb3dd7da" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_3413ab18-18c0-4aa2-a079-d2f9bb3dd7da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_039aceb8-fe9c-43e8-9f11-54c4965c9aca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_3413ab18-18c0-4aa2-a079-d2f9bb3dd7da" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_039aceb8-fe9c-43e8-9f11-54c4965c9aca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_af8b940a-8c21-4872-a718-f79d36a7ee52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_039aceb8-fe9c-43e8-9f11-54c4965c9aca" xlink:to="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_af8b940a-8c21-4872-a718-f79d36a7ee52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_aba82b97-5228-42a6-9661-37a92827e2f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_039aceb8-fe9c-43e8-9f11-54c4965c9aca" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_aba82b97-5228-42a6-9661-37a92827e2f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9af41ad1-5244-4c69-8cf3-5ce8e568d807" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9af41ad1-5244-4c69-8cf3-5ce8e568d807" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9af41ad1-5244-4c69-8cf3-5ce8e568d807_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9af41ad1-5244-4c69-8cf3-5ce8e568d807" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9af41ad1-5244-4c69-8cf3-5ce8e568d807_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1aa2da94-d13f-4c69-b480-f352f0540058" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9af41ad1-5244-4c69-8cf3-5ce8e568d807" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1aa2da94-d13f-4c69-b480-f352f0540058" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GregoryMember_749101cb-eb02-4b5a-ae5e-5d640816f8f9" xlink:href="nrg-20231231.xsd#nrg_GregoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1aa2da94-d13f-4c69-b480-f352f0540058" xlink:to="loc_nrg_GregoryMember_749101cb-eb02-4b5a-ae5e-5d640816f8f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AguaCalienteSolarProjectMember_9c120268-1638-4a9a-b80a-5453133df3e3" xlink:href="nrg-20231231.xsd#nrg_AguaCalienteSolarProjectMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1aa2da94-d13f-4c69-b480-f352f0540058" xlink:to="loc_nrg_AguaCalienteSolarProjectMember_9c120268-1638-4a9a-b80a-5453133df3e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_a2723c15-a3e0-474c-91c4-eb794d6a62b9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:to="loc_srt_OwnershipAxis_a2723c15-a3e0-474c-91c4-eb794d6a62b9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_a2723c15-a3e0-474c-91c4-eb794d6a62b9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_a2723c15-a3e0-474c-91c4-eb794d6a62b9" xlink:to="loc_srt_OwnershipDomain_a2723c15-a3e0-474c-91c4-eb794d6a62b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_6e3fb5eb-1f2f-46c3-8219-283e8e366ed6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_a2723c15-a3e0-474c-91c4-eb794d6a62b9" xlink:to="loc_srt_OwnershipDomain_6e3fb5eb-1f2f-46c3-8219-283e8e366ed6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GregoryMember_7074b2bc-63b6-46a7-99e1-9e7e8184c67f" xlink:href="nrg-20231231.xsd#nrg_GregoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_6e3fb5eb-1f2f-46c3-8219-283e8e366ed6" xlink:to="loc_nrg_GregoryMember_7074b2bc-63b6-46a7-99e1-9e7e8184c67f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_7b6c04db-6507-4fa7-831e-ff67d6e0227a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_def592d4-a407-45ce-b0a3-ad8e8a7356a3" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_7b6c04db-6507-4fa7-831e-ff67d6e0227a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_7b6c04db-6507-4fa7-831e-ff67d6e0227a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_7b6c04db-6507-4fa7-831e-ff67d6e0227a" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_7b6c04db-6507-4fa7-831e-ff67d6e0227a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_41fb728d-c73d-4051-93a6-9d50ae5c9458" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_7b6c04db-6507-4fa7-831e-ff67d6e0227a" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_41fb728d-c73d-4051-93a6-9d50ae5c9458" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndemnificationGuaranteeMember_a83c21c9-a85d-4869-b36b-98a214b4b630" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndemnificationGuaranteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_41fb728d-c73d-4051-93a6-9d50ae5c9458" xlink:to="loc_us-gaap_IndemnificationGuaranteeMember_a83c21c9-a85d-4869-b36b-98a214b4b630" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_df96d4b2-2dcb-4d82-b834-09c2cd2c9079" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_df96d4b2-2dcb-4d82-b834-09c2cd2c9079" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_c0cee804-1914-4bb6-adcc-02285030b716" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_c0cee804-1914-4bb6-adcc-02285030b716" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WorkingCapitalAdjustmentsSaleOfBusiness_3bf885c3-55d0-4631-97ef-755a632f970b" xlink:href="nrg-20231231.xsd#nrg_WorkingCapitalAdjustmentsSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_nrg_WorkingCapitalAdjustmentsSaleOfBusiness_3bf885c3-55d0-4631-97ef-755a632f970b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ProceedsFromDivestitureOfBusinessesNetOfWorkingCapitalAdjustments_0e76b556-5fa8-49eb-908f-facbf30b45a4" xlink:href="nrg-20231231.xsd#nrg_ProceedsFromDivestitureOfBusinessesNetOfWorkingCapitalAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_nrg_ProceedsFromDivestitureOfBusinessesNetOfWorkingCapitalAdjustments_0e76b556-5fa8-49eb-908f-facbf30b45a4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_ffb078ee-40ef-47e4-8889-f029b5527aa6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_ffb078ee-40ef-47e4-8889-f029b5527aa6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_814e4dae-b145-4f87-abea-6d324b454de9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_814e4dae-b145-4f87-abea-6d324b454de9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_17976b4e-3fc0-4ec0-81a9-8baa72b8e036" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_17976b4e-3fc0-4ec0-81a9-8baa72b8e036" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DisposalGroupIncludingDiscontinuedOperationDisposalTransactionFees_55e22141-cf21-448f-954c-5105cf85a503" xlink:href="nrg-20231231.xsd#nrg_DisposalGroupIncludingDiscontinuedOperationDisposalTransactionFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_nrg_DisposalGroupIncludingDiscontinuedOperationDisposalTransactionFees_55e22141-cf21-448f-954c-5105cf85a503" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_d3f49765-d868-4ed5-8741-606f2be7a89c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_d3f49765-d868-4ed5-8741-606f2be7a89c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfEquityMethodInvestments_60ae97b8-ad6a-4c72-94aa-aaf2ff65cfd5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_ProceedsFromSaleOfEquityMethodInvestments_60ae97b8-ad6a-4c72-94aa-aaf2ff65cfd5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_020c0576-d8a6-4114-953b-65d02b712b85" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_020c0576-d8a6-4114-953b-65d02b712b85" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PowerGenerationCapacityMegawatts_5f96ceae-d06f-4bc6-98a3-091fdcd53f9c" xlink:href="nrg-20231231.xsd#nrg_PowerGenerationCapacityMegawatts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_nrg_PowerGenerationCapacityMegawatts_5f96ceae-d06f-4bc6-98a3-091fdcd53f9c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_46e6dab2-e9ec-43f5-8ada-2569c526b1f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_46e6dab2-e9ec-43f5-8ada-2569c526b1f5" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsMaximumExposure_234b47a3-f634-43a3-84e2-f8e88b1ac243" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsMaximumExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_GuaranteeObligationsMaximumExposure_234b47a3-f634-43a3-84e2-f8e88b1ac243" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PercentageofOwnershipSoldofSubsidiary_820d27b4-b79a-4c70-b2ad-c78f2c2ca5bf" xlink:href="nrg-20231231.xsd#nrg_PercentageofOwnershipSoldofSubsidiary"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_nrg_PercentageofOwnershipSoldofSubsidiary_820d27b4-b79a-4c70-b2ad-c78f2c2ca5bf" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCash_fa8cbada-7424-4278-bc7c-b487b30c7556" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCash_fa8cbada-7424-4278-bc7c-b487b30c7556" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DisposalGroupNotDiscontinuedOperationGainLossOnDisposalStatementOfIncomeExtensibleListNotDisclosedFlag_2fc75cc3-6755-4a84-b710-5c1c72a14753" xlink:href="nrg-20231231.xsd#nrg_DisposalGroupNotDiscontinuedOperationGainLossOnDisposalStatementOfIncomeExtensibleListNotDisclosedFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8938b138-4ee8-4eb7-9206-1cb3a4917c86" xlink:to="loc_nrg_DisposalGroupNotDiscontinuedOperationGainLossOnDisposalStatementOfIncomeExtensibleListNotDisclosedFlag_2fc75cc3-6755-4a84-b710-5c1c72a14753" xlink:type="arc" order="16"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AcquisitionsandDispositionsIncomeBeforeIncomeTaxesFromEquityInterestinSTPDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AcquisitionsandDispositionsIncomeBeforeIncomeTaxesFromEquityInterestinSTPDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AcquisitionsandDispositionsIncomeBeforeIncomeTaxesFromEquityInterestinSTPDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_2f39372a-a067-41d6-a418-d6fdb218250b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_6c43a2dc-2a49-44dc-90d8-d8523a168778" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_2f39372a-a067-41d6-a418-d6fdb218250b" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_6c43a2dc-2a49-44dc-90d8-d8523a168778" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_17b2f93a-9a04-4881-af42-eb2a6d22050a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_6c43a2dc-2a49-44dc-90d8-d8523a168778" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_17b2f93a-9a04-4881-af42-eb2a6d22050a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_17b2f93a-9a04-4881-af42-eb2a6d22050a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_17b2f93a-9a04-4881-af42-eb2a6d22050a" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_17b2f93a-9a04-4881-af42-eb2a6d22050a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_f19509ea-8768-4326-b99f-5cc8571c743e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_17b2f93a-9a04-4881-af42-eb2a6d22050a" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_f19509ea-8768-4326-b99f-5cc8571c743e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_2f80bd6f-8858-4c63-b35a-51ec4a298bb2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_f19509ea-8768-4326-b99f-5cc8571c743e" xlink:to="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_2f80bd6f-8858-4c63-b35a-51ec4a298bb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fa7fb20-e8c9-4f45-b144-40eaf672d8c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_6c43a2dc-2a49-44dc-90d8-d8523a168778" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fa7fb20-e8c9-4f45-b144-40eaf672d8c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3fa7fb20-e8c9-4f45-b144-40eaf672d8c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fa7fb20-e8c9-4f45-b144-40eaf672d8c6" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3fa7fb20-e8c9-4f45-b144-40eaf672d8c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_8a9cd1bb-c14e-45fd-989f-1e7ae4572e80" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_3fa7fb20-e8c9-4f45-b144-40eaf672d8c6" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_8a9cd1bb-c14e-45fd-989f-1e7ae4572e80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_ff75ba59-e289-4c42-b34d-32ca8d89e214" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_8a9cd1bb-c14e-45fd-989f-1e7ae4572e80" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_ff75ba59-e289-4c42-b34d-32ca8d89e214" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_1789dfec-5066-4ea8-a6c7-a98bebd240bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_2f39372a-a067-41d6-a418-d6fdb218250b" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_1789dfec-5066-4ea8-a6c7-a98bebd240bc" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsEstimatedCarryingAmountsandFairValueofLongtermDebtDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#FairValueofFinancialInstrumentsEstimatedCarryingAmountsandFairValueofLongtermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsEstimatedCarryingAmountsandFairValueofLongtermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_fa46bc41-1d00-49e3-a7d6-84b094f89541" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_9e897e25-4de4-4be7-a7c1-4eb19b677cc9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_fa46bc41-1d00-49e3-a7d6-84b094f89541" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_9e897e25-4de4-4be7-a7c1-4eb19b677cc9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_8b3d379a-d95d-4539-b8af-79800497f704" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_9e897e25-4de4-4be7-a7c1-4eb19b677cc9" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_8b3d379a-d95d-4539-b8af-79800497f704" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8b3d379a-d95d-4539-b8af-79800497f704_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_8b3d379a-d95d-4539-b8af-79800497f704" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_8b3d379a-d95d-4539-b8af-79800497f704_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e32a4a88-8703-4f56-a732-d05e4523aab8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_8b3d379a-d95d-4539-b8af-79800497f704" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e32a4a88-8703-4f56-a732-d05e4523aab8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_48757b80-90de-4d2c-87c2-532f6df64c5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e32a4a88-8703-4f56-a732-d05e4523aab8" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_48757b80-90de-4d2c-87c2-532f6df64c5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_f65bbebd-5f7d-4231-b369-638db46e371f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e32a4a88-8703-4f56-a732-d05e4523aab8" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_f65bbebd-5f7d-4231-b369-638db46e371f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_d2ba411b-4c1b-46df-a34b-088aaaf64729" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e32a4a88-8703-4f56-a732-d05e4523aab8" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_d2ba411b-4c1b-46df-a34b-088aaaf64729" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_eebf4d4b-7019-44ee-9c35-89f7fabfb5e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_9e897e25-4de4-4be7-a7c1-4eb19b677cc9" xlink:to="loc_us-gaap_FinancialInstrumentAxis_eebf4d4b-7019-44ee-9c35-89f7fabfb5e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_eebf4d4b-7019-44ee-9c35-89f7fabfb5e8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_eebf4d4b-7019-44ee-9c35-89f7fabfb5e8" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_eebf4d4b-7019-44ee-9c35-89f7fabfb5e8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_242ecbbd-16a8-409f-b673-52e360a9b86a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_eebf4d4b-7019-44ee-9c35-89f7fabfb5e8" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_242ecbbd-16a8-409f-b673-52e360a9b86a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorDebtObligationsMember_0d5dbcde-8299-417f-97be-c506b555aba3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorDebtObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_242ecbbd-16a8-409f-b673-52e360a9b86a" xlink:to="loc_us-gaap_SeniorDebtObligationsMember_0d5dbcde-8299-417f-97be-c506b555aba3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDebtSecuritiesMember_00d91d7f-bed0-4d84-b549-7941773341a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_242ecbbd-16a8-409f-b673-52e360a9b86a" xlink:to="loc_us-gaap_OtherDebtSecuritiesMember_00d91d7f-bed0-4d84-b549-7941773341a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_4a77d23a-9a91-40db-b664-e2d56c180c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_fa46bc41-1d00-49e3-a7d6-84b094f89541" xlink:to="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_4a77d23a-9a91-40db-b664-e2d56c180c7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_01c99779-db00-4c03-a143-391c30f2a6dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_4a77d23a-9a91-40db-b664-e2d56c180c7e" xlink:to="loc_us-gaap_LongTermDebt_01c99779-db00-4c03-a143-391c30f2a6dc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsAssetsandLiabilitiesMeasuredandRecordedatFairValueDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#FairValueofFinancialInstrumentsAssetsandLiabilitiesMeasuredandRecordedatFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsAssetsandLiabilitiesMeasuredandRecordedatFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_136b141c-7273-4248-b93b-1ca360d20aa0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_136b141c-7273-4248-b93b-1ca360d20aa0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0162955e-e2c6-4b4f-be0e-95f0b22b6c9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_136b141c-7273-4248-b93b-1ca360d20aa0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0162955e-e2c6-4b4f-be0e-95f0b22b6c9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0162955e-e2c6-4b4f-be0e-95f0b22b6c9d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0162955e-e2c6-4b4f-be0e-95f0b22b6c9d" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0162955e-e2c6-4b4f-be0e-95f0b22b6c9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5416d9d6-90fe-4740-94c2-84311a4eb449" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_0162955e-e2c6-4b4f-be0e-95f0b22b6c9d" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5416d9d6-90fe-4740-94c2-84311a4eb449" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_6c84f9a6-3680-414b-ad84-1a985dfe0ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5416d9d6-90fe-4740-94c2-84311a4eb449" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_6c84f9a6-3680-414b-ad84-1a985dfe0ebf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_18eb5a1f-20bf-4d7c-a69b-9f8c5ea4784c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5416d9d6-90fe-4740-94c2-84311a4eb449" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_18eb5a1f-20bf-4d7c-a69b-9f8c5ea4784c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_3950df35-84d2-4390-827a-14c50314040e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5416d9d6-90fe-4740-94c2-84311a4eb449" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_3950df35-84d2-4390-827a-14c50314040e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_5880cea7-b642-42ea-a4bc-136666175286" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5416d9d6-90fe-4740-94c2-84311a4eb449" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_5880cea7-b642-42ea-a4bc-136666175286" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_1179d23b-ddea-4f7d-acd2-62712f4382f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_136b141c-7273-4248-b93b-1ca360d20aa0" xlink:to="loc_us-gaap_FinancialInstrumentAxis_1179d23b-ddea-4f7d-acd2-62712f4382f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1179d23b-ddea-4f7d-acd2-62712f4382f5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_1179d23b-ddea-4f7d-acd2-62712f4382f5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1179d23b-ddea-4f7d-acd2-62712f4382f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_1179d23b-ddea-4f7d-acd2-62712f4382f5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_17526d5d-3b6d-45f5-bbd5-f9e8d59b3eec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_17526d5d-3b6d-45f5-bbd5-f9e8d59b3eec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_a2e54d55-c10a-4c6c-85c8-14f0e8d6e425" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_a2e54d55-c10a-4c6c-85c8-14f0e8d6e425" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_32225456-834f-4882-af97-7d919a26bb7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_32225456-834f-4882-af97-7d919a26bb7e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_a2d879fa-54ef-4a34-a0d4-74aeb804fcbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_a2d879fa-54ef-4a34-a0d4-74aeb804fcbc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_e505ddaf-2379-4294-a0f3-0a3cdddaa658" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_e505ddaf-2379-4294-a0f3-0a3cdddaa658" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_54501fe9-c6e9-467f-93f8-8e5bf8ee5564" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_us-gaap_EquitySecuritiesMember_54501fe9-c6e9-467f-93f8-8e5bf8ee5564" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_87b015da-42da-430e-8943-eec1c78236c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_87b015da-42da-430e-8943-eec1c78236c2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EquitySecuritiesNuclearTrustFundMember_e2f0032e-8f44-4c69-a94a-01163fadd3cd" xlink:href="nrg-20231231.xsd#nrg_EquitySecuritiesNuclearTrustFundMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_71166480-5347-45d2-998d-c41143763b03" xlink:to="loc_nrg_EquitySecuritiesNuclearTrustFundMember_e2f0032e-8f44-4c69-a94a-01163fadd3cd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_51db0503-d069-4a7c-9ac6-4db9afbddfd1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_136b141c-7273-4248-b93b-1ca360d20aa0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_51db0503-d069-4a7c-9ac6-4db9afbddfd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_51db0503-d069-4a7c-9ac6-4db9afbddfd1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_51db0503-d069-4a7c-9ac6-4db9afbddfd1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_51db0503-d069-4a7c-9ac6-4db9afbddfd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_16c2adb8-beed-48f5-bf6a-909609ee1327" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_51db0503-d069-4a7c-9ac6-4db9afbddfd1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_16c2adb8-beed-48f5-bf6a-909609ee1327" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_901f7c88-0ced-4c2d-888f-4b8e1d28d7ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_16c2adb8-beed-48f5-bf6a-909609ee1327" xlink:to="loc_us-gaap_InterestRateContractMember_901f7c88-0ced-4c2d-888f-4b8e1d28d7ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_ac897187-7a6b-4c98-8446-248d579bde51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_16c2adb8-beed-48f5-bf6a-909609ee1327" xlink:to="loc_us-gaap_ForeignExchangeContractMember_ac897187-7a6b-4c98-8446-248d579bde51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_c94ea415-da70-4391-a8d9-cc79b77f5235" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_16c2adb8-beed-48f5-bf6a-909609ee1327" xlink:to="loc_us-gaap_CommodityContractMember_c94ea415-da70-4391-a8d9-cc79b77f5235" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramMember_5b5017e6-554e-4dfe-b188-ae5b41da2b19" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_16c2adb8-beed-48f5-bf6a-909609ee1327" xlink:to="loc_nrg_ConsumerFinancingProgramMember_5b5017e6-554e-4dfe-b188-ae5b41da2b19" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_9343dfb8-b869-4e31-9b21-26c45f3c8458" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_9343dfb8-b869-4e31-9b21-26c45f3c8458" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NuclearTrustFundInvestmentsAbstract_1c657191-368e-411b-b86d-57aee4cc83ee" xlink:href="nrg-20231231.xsd#nrg_NuclearTrustFundInvestmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_nrg_NuclearTrustFundInvestmentsAbstract_1c657191-368e-411b-b86d-57aee4cc83ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningFundInvestments_e93a0757-0cad-4b5e-b95f-321c7b66a729" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DecommissioningFundInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_NuclearTrustFundInvestmentsAbstract_1c657191-368e-411b-b86d-57aee4cc83ee" xlink:to="loc_us-gaap_DecommissioningFundInvestments_e93a0757-0cad-4b5e-b95f-321c7b66a729" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract_5a3633bf-0c12-413c-b981-2908f6c4bfc7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract_5a3633bf-0c12-413c-b981-2908f6c4bfc7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_aa6cba56-d815-4ccd-a9e1-ca064987808c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsOwnedAtFairValueByTypeAbstract_5a3633bf-0c12-413c-b981-2908f6c4bfc7" xlink:to="loc_us-gaap_FinancialInstrumentsOwnedUSGovernmentAndAgencyObligationsAtFairValue_aa6cba56-d815-4ccd-a9e1-ca064987808c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsAbstract_9785c75f-4859-4a09-868a-315dc81b8b96" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_us-gaap_DerivativeAssetsAbstract_9785c75f-4859-4a09-868a-315dc81b8b96" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_cf8da5a2-bb96-46ed-ac0d-9be6425e3659" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_9785c75f-4859-4a09-868a-315dc81b8b96" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_cf8da5a2-bb96-46ed-ac0d-9be6425e3659" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MeasuredUsingNetAssetValuePracticalExpedientAbstract_f38e7352-5f51-4455-b1b8-f2f00deea42e" xlink:href="nrg-20231231.xsd#nrg_MeasuredUsingNetAssetValuePracticalExpedientAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_nrg_MeasuredUsingNetAssetValuePracticalExpedientAbstract_f38e7352-5f51-4455-b1b8-f2f00deea42e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_57f1fffb-d76e-43d2-b51e-323a75f1dbe5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_MeasuredUsingNetAssetValuePracticalExpedientAbstract_f38e7352-5f51-4455-b1b8-f2f00deea42e" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_57f1fffb-d76e-43d2-b51e-323a75f1dbe5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_07317e73-74f8-4df1-b59b-bb28fa32110a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_07317e73-74f8-4df1-b59b-bb28fa32110a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueNetAbstract_06b40010-1e95-45c1-835e-ab1b10a9b6aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityFairValueNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueNetAbstract_06b40010-1e95-45c1-835e-ab1b10a9b6aa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_d259a00f-316b-4329-85d3-629c3b9df178" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilityFairValueNetAbstract_06b40010-1e95-45c1-835e-ab1b10a9b6aa" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_d259a00f-316b-4329-85d3-629c3b9df178" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_9cb4d333-7a79-43fb-99b9-727d245c5bb8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3f080536-6ced-413c-a931-7134cf80d3aa" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_9cb4d333-7a79-43fb-99b9-727d245c5bb8" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsReconciliationofLevel3FinancialInstrumentsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#FairValueofFinancialInstrumentsReconciliationofLevel3FinancialInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsReconciliationofLevel3FinancialInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract_e46388de-b888-4451-99c9-3b68aabebce4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b10f9bd0-e4f4-470c-a384-ee3f91ce001f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract_e46388de-b888-4451-99c9-3b68aabebce4" xlink:to="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b10f9bd0-e4f4-470c-a384-ee3f91ce001f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_84383c89-f7a3-47ef-a654-739ecd9a3938" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b10f9bd0-e4f4-470c-a384-ee3f91ce001f" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_84383c89-f7a3-47ef-a654-739ecd9a3938" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_84383c89-f7a3-47ef-a654-739ecd9a3938_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_84383c89-f7a3-47ef-a654-739ecd9a3938" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_84383c89-f7a3-47ef-a654-739ecd9a3938_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b25e5a2-4fa2-4206-a362-9d6f16c5614d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_84383c89-f7a3-47ef-a654-739ecd9a3938" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b25e5a2-4fa2-4206-a362-9d6f16c5614d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_4d2fd2a8-8603-4d4a-a8f6-07ad20a0b8c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b25e5a2-4fa2-4206-a362-9d6f16c5614d" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_4d2fd2a8-8603-4d4a-a8f6-07ad20a0b8c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_e80ee5b2-c175-4cd4-8312-e5a1a0790ffc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b10f9bd0-e4f4-470c-a384-ee3f91ce001f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_e80ee5b2-c175-4cd4-8312-e5a1a0790ffc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e80ee5b2-c175-4cd4-8312-e5a1a0790ffc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_e80ee5b2-c175-4cd4-8312-e5a1a0790ffc" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e80ee5b2-c175-4cd4-8312-e5a1a0790ffc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_0572b9f4-12c4-4ccc-93d2-51ea6fbc3d46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_e80ee5b2-c175-4cd4-8312-e5a1a0790ffc" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_0572b9f4-12c4-4ccc-93d2-51ea6fbc3d46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_07c9397f-38cd-40f6-857f-8b37168c34d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_0572b9f4-12c4-4ccc-93d2-51ea6fbc3d46" xlink:to="loc_us-gaap_DerivativeMember_07c9397f-38cd-40f6-857f-8b37168c34d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract_e46388de-b888-4451-99c9-3b68aabebce4" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_f447d0fd-5a94-4cb7-b722-c0ac75bff402" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_f447d0fd-5a94-4cb7-b722-c0ac75bff402" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_571761e9-a833-40b1-9483-90e6038864c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_571761e9-a833-40b1-9483-90e6038864c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases_00600731-367c-4165-9ff0-976e9e95d0d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases_00600731-367c-4165-9ff0-976e9e95d0d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3_11fbf17c-86c6-43ce-b5e2-31a1d21b72d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersIntoLevel3_11fbf17c-86c6-43ce-b5e2-31a1d21b72d6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3_0b2057cf-2c4f-4beb-9049-79f85effcabd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3_0b2057cf-2c4f-4beb-9049-79f85effcabd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_8554dfa1-f9f9-4616-8667-accdb3940fa0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_e8406f36-5714-456d-8e08-881f443b92e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_ad282e0b-500e-4fb3-ade8-75951e739d45" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss_e8406f36-5714-456d-8e08-881f443b92e4" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsContractualObligationsFromtheConsumerFinancingProgramDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#FairValueofFinancialInstrumentsContractualObligationsFromtheConsumerFinancingProgramDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsContractualObligationsFromtheConsumerFinancingProgramDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract_96e23188-b505-4ef5-a7d6-55069d34d6cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b4296d27-ca11-4fe9-b9ae-e0584e187e61" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract_96e23188-b505-4ef5-a7d6-55069d34d6cb" xlink:to="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b4296d27-ca11-4fe9-b9ae-e0584e187e61" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_43e0df29-eed9-4cd0-acc9-08ae6daa9bdb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b4296d27-ca11-4fe9-b9ae-e0584e187e61" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_43e0df29-eed9-4cd0-acc9-08ae6daa9bdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_43e0df29-eed9-4cd0-acc9-08ae6daa9bdb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_43e0df29-eed9-4cd0-acc9-08ae6daa9bdb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_43e0df29-eed9-4cd0-acc9-08ae6daa9bdb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2bc60573-d383-4492-b52c-e5ed37188b86" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_43e0df29-eed9-4cd0-acc9-08ae6daa9bdb" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2bc60573-d383-4492-b52c-e5ed37188b86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_934d0fd2-dbdf-41ea-a8cd-f8eb90ee3e1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2bc60573-d383-4492-b52c-e5ed37188b86" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_934d0fd2-dbdf-41ea-a8cd-f8eb90ee3e1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_406d9519-48f4-433d-8f26-aeb9b3c576e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b4296d27-ca11-4fe9-b9ae-e0584e187e61" xlink:to="loc_us-gaap_FinancialInstrumentAxis_406d9519-48f4-433d-8f26-aeb9b3c576e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_406d9519-48f4-433d-8f26-aeb9b3c576e1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_406d9519-48f4-433d-8f26-aeb9b3c576e1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_406d9519-48f4-433d-8f26-aeb9b3c576e1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3a36bfb1-2e56-4bc2-8fea-7570c8657673" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_406d9519-48f4-433d-8f26-aeb9b3c576e1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3a36bfb1-2e56-4bc2-8fea-7570c8657673" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMember_b8f5762e-8b73-4e33-92e7-f9aea3ef1190" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3a36bfb1-2e56-4bc2-8fea-7570c8657673" xlink:to="loc_us-gaap_DerivativeMember_b8f5762e-8b73-4e33-92e7-f9aea3ef1190" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_9162613c-38d3-4c39-aa60-2733524b6a95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsTable_b4296d27-ca11-4fe9-b9ae-e0584e187e61" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_9162613c-38d3-4c39-aa60-2733524b6a95" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_9162613c-38d3-4c39-aa60-2733524b6a95_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9162613c-38d3-4c39-aa60-2733524b6a95" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_9162613c-38d3-4c39-aa60-2733524b6a95_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_14caab04-8436-4126-b1cf-ea9bb36cf58b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9162613c-38d3-4c39-aa60-2733524b6a95" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_14caab04-8436-4126-b1cf-ea9bb36cf58b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramMember_f5d2b86c-36a8-4c89-b6e8-ffea6f8bd53a" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_14caab04-8436-4126-b1cf-ea9bb36cf58b" xlink:to="loc_nrg_ConsumerFinancingProgramMember_f5d2b86c-36a8-4c89-b6e8-ffea6f8bd53a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_505a93ba-a594-49ff-a020-8ed0293889c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarningsAbstract_96e23188-b505-4ef5-a7d6-55069d34d6cb" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_505a93ba-a594-49ff-a020-8ed0293889c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_abbe2970-d74b-48d3-a0cc-97c81f381cd2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_505a93ba-a594-49ff-a020-8ed0293889c5" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_abbe2970-d74b-48d3-a0cc-97c81f381cd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationAcquisition_6d4b7f79-6a73-43d9-9d2d-59aa15a0c56e" xlink:href="nrg-20231231.xsd#nrg_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_505a93ba-a594-49ff-a020-8ed0293889c5" xlink:to="loc_nrg_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationAcquisition_6d4b7f79-6a73-43d9-9d2d-59aa15a0c56e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases_27e2b519-031e-4e9d-b972-db00eae505d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_505a93ba-a594-49ff-a020-8ed0293889c5" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases_27e2b519-031e-4e9d-b972-db00eae505d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_b8f50576-2c5e-428b-9e06-1e68a1102804" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_505a93ba-a594-49ff-a020-8ed0293889c5" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements_b8f50576-2c5e-428b-9e06-1e68a1102804" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_4229ed04-6025-4ea7-a5ba-8dafbe6154be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationRollForward_505a93ba-a594-49ff-a020-8ed0293889c5" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings_4229ed04-6025-4ea7-a5ba-8dafbe6154be" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs_846c9921-abea-4a3f-96c8-5152b46ab676" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsSignificantUnobservableInputsUsedinFairValueofLevel3PositionsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#FairValueofFinancialInstrumentsSignificantUnobservableInputsUsedinFairValueofLevel3PositionsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsSignificantUnobservableInputsUsedinFairValueofLevel3PositionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_efff3318-893f-4722-ab08-40fc10ec646b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOptionQuantitativeDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_efff3318-893f-4722-ab08-40fc10ec646b" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_a5013934-4950-4636-ae93-961aa1df2a59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_a5013934-4950-4636-ae93-961aa1df2a59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a5013934-4950-4636-ae93-961aa1df2a59_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a5013934-4950-4636-ae93-961aa1df2a59" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a5013934-4950-4636-ae93-961aa1df2a59_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_0351d252-e7bb-4934-a996-614a42ad668c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a5013934-4950-4636-ae93-961aa1df2a59" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_0351d252-e7bb-4934-a996-614a42ad668c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_6cea0604-5bb9-4b0b-9c7f-37edfc404722" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0351d252-e7bb-4934-a996-614a42ad668c" xlink:to="loc_us-gaap_CommodityContractMember_6cea0604-5bb9-4b0b-9c7f-37edfc404722" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_ef567a59-db3f-4aef-b5ac-ecbc44c509db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0351d252-e7bb-4934-a996-614a42ad668c" xlink:to="loc_us-gaap_InterestRateContractMember_ef567a59-db3f-4aef-b5ac-ecbc44c509db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapacityContractsMember_d8a09465-de5e-4a23-b3c8-283ee5695b08" xlink:href="nrg-20231231.xsd#nrg_CapacityContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0351d252-e7bb-4934-a996-614a42ad668c" xlink:to="loc_nrg_CapacityContractsMember_d8a09465-de5e-4a23-b3c8-283ee5695b08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_7b71e4a5-30c6-4455-9555-007dabc1b128" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_7b71e4a5-30c6-4455-9555-007dabc1b128" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_7b71e4a5-30c6-4455-9555-007dabc1b128_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_7b71e4a5-30c6-4455-9555-007dabc1b128" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_7b71e4a5-30c6-4455-9555-007dabc1b128_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_8c15e88c-f524-45a6-80f7-59d21b09d167" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_7b71e4a5-30c6-4455-9555-007dabc1b128" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_8c15e88c-f524-45a6-80f7-59d21b09d167" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_7e2c84f2-70f6-48ec-a92e-e44278725668" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_8c15e88c-f524-45a6-80f7-59d21b09d167" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_7e2c84f2-70f6-48ec-a92e-e44278725668" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativesByUnderlyingAssetsAxis_625666bf-5c18-4cf2-8137-e8e55474aace" xlink:href="nrg-20231231.xsd#nrg_DerivativesByUnderlyingAssetsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:to="loc_nrg_DerivativesByUnderlyingAssetsAxis_625666bf-5c18-4cf2-8137-e8e55474aace" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativesByUnderlyingAssetsDomain_625666bf-5c18-4cf2-8137-e8e55474aace_default" xlink:href="nrg-20231231.xsd#nrg_DerivativesByUnderlyingAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsAxis_625666bf-5c18-4cf2-8137-e8e55474aace" xlink:to="loc_nrg_DerivativesByUnderlyingAssetsDomain_625666bf-5c18-4cf2-8137-e8e55474aace_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:href="nrg-20231231.xsd#nrg_DerivativesByUnderlyingAssetsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsAxis_625666bf-5c18-4cf2-8137-e8e55474aace" xlink:to="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NaturalGasContractMember_a1817cb7-6e93-4318-87a5-4f8d9891514b" xlink:href="nrg-20231231.xsd#nrg_NaturalGasContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:to="loc_nrg_NaturalGasContractMember_a1817cb7-6e93-4318-87a5-4f8d9891514b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PowerContractsMember_b37ddcf4-312d-4409-987d-20da73ac0a43" xlink:href="nrg-20231231.xsd#nrg_PowerContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:to="loc_nrg_PowerContractsMember_b37ddcf4-312d-4409-987d-20da73ac0a43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapacityContractsMember_90edb1e5-75b5-4843-9f89-95c8fc71af5c" xlink:href="nrg-20231231.xsd#nrg_CapacityContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:to="loc_nrg_CapacityContractsMember_90edb1e5-75b5-4843-9f89-95c8fc71af5c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RenewableEnergyCertificatesMember_d6b91d6b-00c4-4eea-a7a6-21790c63db5e" xlink:href="nrg-20231231.xsd#nrg_RenewableEnergyCertificatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:to="loc_nrg_RenewableEnergyCertificatesMember_d6b91d6b-00c4-4eea-a7a6-21790c63db5e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FinancialTransmissionRightsMember_b0686798-db0a-4bb1-a519-64ded3f906ae" xlink:href="nrg-20231231.xsd#nrg_FinancialTransmissionRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:to="loc_nrg_FinancialTransmissionRightsMember_b0686798-db0a-4bb1-a519-64ded3f906ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramMember_7d909e91-4dc2-4461-aff9-614684376a57" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DerivativesByUnderlyingAssetsDomain_cff5da48-f41a-42ca-ac3b-d8b0b13a63ba" xlink:to="loc_nrg_ConsumerFinancingProgramMember_7d909e91-4dc2-4461-aff9-614684376a57" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bf122a4b-34df-4edd-a370-27f5f66f1b36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bf122a4b-34df-4edd-a370-27f5f66f1b36" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bf122a4b-34df-4edd-a370-27f5f66f1b36_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bf122a4b-34df-4edd-a370-27f5f66f1b36" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bf122a4b-34df-4edd-a370-27f5f66f1b36_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1c4cae25-2eb8-46dd-9c5e-8947926e8994" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_bf122a4b-34df-4edd-a370-27f5f66f1b36" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1c4cae25-2eb8-46dd-9c5e-8947926e8994" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_7b9bffd0-4818-4691-8cdc-4d5483bec5f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1c4cae25-2eb8-46dd-9c5e-8947926e8994" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_7b9bffd0-4818-4691-8cdc-4d5483bec5f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_50250339-212e-46c1-abeb-759487353640" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:to="loc_srt_RangeAxis_50250339-212e-46c1-abeb-759487353640" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_50250339-212e-46c1-abeb-759487353640_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_50250339-212e-46c1-abeb-759487353640" xlink:to="loc_srt_RangeMember_50250339-212e-46c1-abeb-759487353640_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a0c668a8-786b-4fe7-b6cc-d5f34194af83" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_50250339-212e-46c1-abeb-759487353640" xlink:to="loc_srt_RangeMember_a0c668a8-786b-4fe7-b6cc-d5f34194af83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_25efaf19-e50f-465e-8eec-baeed6c97d36" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a0c668a8-786b-4fe7-b6cc-d5f34194af83" xlink:to="loc_srt_MinimumMember_25efaf19-e50f-465e-8eec-baeed6c97d36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_de60fc20-5574-4c0e-ad26-118901870e38" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a0c668a8-786b-4fe7-b6cc-d5f34194af83" xlink:to="loc_srt_MaximumMember_de60fc20-5574-4c0e-ad26-118901870e38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_66191390-6bd2-4a3d-9186-0ae8288880af" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a0c668a8-786b-4fe7-b6cc-d5f34194af83" xlink:to="loc_srt_WeightedAverageMember_66191390-6bd2-4a3d-9186-0ae8288880af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_9749a880-946d-4061-9b28-2cd1b78be88a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_9749a880-946d-4061-9b28-2cd1b78be88a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_9749a880-946d-4061-9b28-2cd1b78be88a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_9749a880-946d-4061-9b28-2cd1b78be88a" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_9749a880-946d-4061-9b28-2cd1b78be88a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_9ccdcfa2-0a25-47be-a462-4c61df279ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_9749a880-946d-4061-9b28-2cd1b78be88a" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_9ccdcfa2-0a25-47be-a462-4c61df279ecd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputCommodityForwardPriceMember_1d2c6bf7-afd9-4b2f-a0c9-f5560c4da417" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputCommodityForwardPriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_9ccdcfa2-0a25-47be-a462-4c61df279ecd" xlink:to="loc_us-gaap_MeasurementInputCommodityForwardPriceMember_1d2c6bf7-afd9-4b2f-a0c9-f5560c4da417" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MeasurementInputAuctionPriceMember_bdd0a040-4bf8-4881-8db9-319e43808f45" xlink:href="nrg-20231231.xsd#nrg_MeasurementInputAuctionPriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_9ccdcfa2-0a25-47be-a462-4c61df279ecd" xlink:to="loc_nrg_MeasurementInputAuctionPriceMember_bdd0a040-4bf8-4881-8db9-319e43808f45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MeasurementInputCollateralDefaultRateMember_db470afe-9226-490b-8615-05fde48ed9d0" xlink:href="nrg-20231231.xsd#nrg_MeasurementInputCollateralDefaultRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_9ccdcfa2-0a25-47be-a462-4c61df279ecd" xlink:to="loc_nrg_MeasurementInputCollateralDefaultRateMember_db470afe-9226-490b-8615-05fde48ed9d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MeasurementInputCollateralPrepaymentRateMember_fd05b98b-cfb2-4b73-bacb-80b956450c64" xlink:href="nrg-20231231.xsd#nrg_MeasurementInputCollateralPrepaymentRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_9ccdcfa2-0a25-47be-a462-4c61df279ecd" xlink:to="loc_nrg_MeasurementInputCollateralPrepaymentRateMember_fd05b98b-cfb2-4b73-bacb-80b956450c64" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputLossSeverityMember_9a1a4bc9-2404-4ecb-b8b9-918d3f04c509" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputLossSeverityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_9ccdcfa2-0a25-47be-a462-4c61df279ecd" xlink:to="loc_us-gaap_MeasurementInputLossSeverityMember_9a1a4bc9-2404-4ecb-b8b9-918d3f04c509" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_cd4a97aa-f25c-47b4-bf84-e52012a5c1da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_3061fff4-6176-434b-a6ef-54126b729b61" xlink:to="loc_us-gaap_ValuationTechniqueAxis_cd4a97aa-f25c-47b4-bf84-e52012a5c1da" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_cd4a97aa-f25c-47b4-bf84-e52012a5c1da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_cd4a97aa-f25c-47b4-bf84-e52012a5c1da" xlink:to="loc_us-gaap_ValuationTechniqueDomain_cd4a97aa-f25c-47b4-bf84-e52012a5c1da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_7048f7da-efa6-47d8-9f03-c56ffc8842ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_cd4a97aa-f25c-47b4-bf84-e52012a5c1da" xlink:to="loc_us-gaap_ValuationTechniqueDomain_7048f7da-efa6-47d8-9f03-c56ffc8842ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_01071518-884f-4121-974e-7863e8cc03ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_7048f7da-efa6-47d8-9f03-c56ffc8842ca" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_01071518-884f-4121-974e-7863e8cc03ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_99e0b4b8-fcf1-403e-bbd0-28c4ccd83042" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_efff3318-893f-4722-ab08-40fc10ec646b" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_99e0b4b8-fcf1-403e-bbd0-28c4ccd83042" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_8a891b88-8032-41f9-8aca-9384a25524e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_99e0b4b8-fcf1-403e-bbd0-28c4ccd83042" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_8a891b88-8032-41f9-8aca-9384a25524e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_d009c06c-3ca9-4166-8157-7a91c2235669" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_efff3318-893f-4722-ab08-40fc10ec646b" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_d009c06c-3ca9-4166-8157-7a91c2235669" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_eaf26748-a3d1-40ce-bf8d-a7a2658fb7dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_d009c06c-3ca9-4166-8157-7a91c2235669" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_eaf26748-a3d1-40ce-bf8d-a7a2658fb7dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsQuantitativeInformationAbstract_02f14820-1174-4829-bec5-bc2e5ca22372" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsQuantitativeInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_efff3318-893f-4722-ab08-40fc10ec646b" xlink:to="loc_us-gaap_FairValueInputsQuantitativeInformationAbstract_02f14820-1174-4829-bec5-bc2e5ca22372" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetLiabilityNetMeasurementInput_28e1f008-e001-4dbb-86e2-4396f26d8ecb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetLiabilityNetMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsQuantitativeInformationAbstract_02f14820-1174-4829-bec5-bc2e5ca22372" xlink:to="loc_us-gaap_DerivativeAssetLiabilityNetMeasurementInput_28e1f008-e001-4dbb-86e2-4396f26d8ecb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityMeasurementInput_f907e897-c720-4bca-aa9e-6caa0b8f42dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsQuantitativeInformationAbstract_02f14820-1174-4829-bec5-bc2e5ca22372" xlink:to="loc_us-gaap_DerivativeLiabilityMeasurementInput_f907e897-c720-4bca-aa9e-6caa0b8f42dc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeLiabilityNotSubjectToMasterNettingArrangementCollateralRightToReclaimCashNotOffset_f840cb2e-966f-4712-995a-5a7cd5fd71df" xlink:href="nrg-20231231.xsd#nrg_DerivativeLiabilityNotSubjectToMasterNettingArrangementCollateralRightToReclaimCashNotOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_efff3318-893f-4722-ab08-40fc10ec646b" xlink:to="loc_nrg_DerivativeLiabilityNotSubjectToMasterNettingArrangementCollateralRightToReclaimCashNotOffset_f840cb2e-966f-4712-995a-5a7cd5fd71df" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeAssetNotSubjectToMasterNettingArrangementCollateralObligationToReturnCashNotOffset_5ee15f7a-d762-4a8f-9080-b96b124676dc" xlink:href="nrg-20231231.xsd#nrg_DerivativeAssetNotSubjectToMasterNettingArrangementCollateralObligationToReturnCashNotOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOptionQuantitativeDisclosuresLineItems_efff3318-893f-4722-ab08-40fc10ec646b" xlink:to="loc_nrg_DerivativeAssetNotSubjectToMasterNettingArrangementCollateralObligationToReturnCashNotOffset_5ee15f7a-d762-4a8f-9080-b96b124676dc" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsCounterpartyCreditRiskDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#FairValueofFinancialInstrumentsCounterpartyCreditRiskDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsCounterpartyCreditRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskTable_39303cd8-fb29-4cd9-bc09-764a9fe296fb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueConcentrationOfRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskTable_39303cd8-fb29-4cd9-bc09-764a9fe296fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyRiskByInstitutionAxis_c1f27337-3a58-4abe-b61c-6a3e79c666a8" xlink:href="nrg-20231231.xsd#nrg_CounterpartyRiskByInstitutionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskTable_39303cd8-fb29-4cd9-bc09-764a9fe296fb" xlink:to="loc_nrg_CounterpartyRiskByInstitutionAxis_c1f27337-3a58-4abe-b61c-6a3e79c666a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyRiskByInstitutionDomain_c1f27337-3a58-4abe-b61c-6a3e79c666a8_default" xlink:href="nrg-20231231.xsd#nrg_CounterpartyRiskByInstitutionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nrg_CounterpartyRiskByInstitutionAxis_c1f27337-3a58-4abe-b61c-6a3e79c666a8" xlink:to="loc_nrg_CounterpartyRiskByInstitutionDomain_c1f27337-3a58-4abe-b61c-6a3e79c666a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyRiskByInstitutionDomain_df6e0e54-42b2-4d82-9a14-0114d142c09d" xlink:href="nrg-20231231.xsd#nrg_CounterpartyRiskByInstitutionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nrg_CounterpartyRiskByInstitutionAxis_c1f27337-3a58-4abe-b61c-6a3e79c666a8" xlink:to="loc_nrg_CounterpartyRiskByInstitutionDomain_df6e0e54-42b2-4d82-9a14-0114d142c09d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_UtilitiesEnergyMerchantsMarketersAndOtherMember_990b1c59-c621-4f41-81c7-67a01fd5d12f" xlink:href="nrg-20231231.xsd#nrg_UtilitiesEnergyMerchantsMarketersAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CounterpartyRiskByInstitutionDomain_df6e0e54-42b2-4d82-9a14-0114d142c09d" xlink:to="loc_nrg_UtilitiesEnergyMerchantsMarketersAndOtherMember_990b1c59-c621-4f41-81c7-67a01fd5d12f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FinancialInstitutionsMember_f4a341e2-0a29-486d-a81e-8084578391ea" xlink:href="nrg-20231231.xsd#nrg_FinancialInstitutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CounterpartyRiskByInstitutionDomain_df6e0e54-42b2-4d82-9a14-0114d142c09d" xlink:to="loc_nrg_FinancialInstitutionsMember_f4a341e2-0a29-486d-a81e-8084578391ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyRiskByInvestmentGradeAxis_044aee1a-06f3-4372-8323-a66108ac0684" xlink:href="nrg-20231231.xsd#nrg_CounterpartyRiskByInvestmentGradeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskTable_39303cd8-fb29-4cd9-bc09-764a9fe296fb" xlink:to="loc_nrg_CounterpartyRiskByInvestmentGradeAxis_044aee1a-06f3-4372-8323-a66108ac0684" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyRiskByInvestmentGradeDomain_044aee1a-06f3-4372-8323-a66108ac0684_default" xlink:href="nrg-20231231.xsd#nrg_CounterpartyRiskByInvestmentGradeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nrg_CounterpartyRiskByInvestmentGradeAxis_044aee1a-06f3-4372-8323-a66108ac0684" xlink:to="loc_nrg_CounterpartyRiskByInvestmentGradeDomain_044aee1a-06f3-4372-8323-a66108ac0684_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyRiskByInvestmentGradeDomain_073e9234-7e77-461d-b8eb-8f792002ed92" xlink:href="nrg-20231231.xsd#nrg_CounterpartyRiskByInvestmentGradeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nrg_CounterpartyRiskByInvestmentGradeAxis_044aee1a-06f3-4372-8323-a66108ac0684" xlink:to="loc_nrg_CounterpartyRiskByInvestmentGradeDomain_073e9234-7e77-461d-b8eb-8f792002ed92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExternalCreditRatingInvestmentGradeMember_a8c5f7c4-4e54-4eb7-8cd4-204d5623e9a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExternalCreditRatingInvestmentGradeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CounterpartyRiskByInvestmentGradeDomain_073e9234-7e77-461d-b8eb-8f792002ed92" xlink:to="loc_us-gaap_ExternalCreditRatingInvestmentGradeMember_a8c5f7c4-4e54-4eb7-8cd4-204d5623e9a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ExternalCreditRatingNotRatedMember_b2df3988-1c3e-405e-b7ad-6c820a75cfbf" xlink:href="nrg-20231231.xsd#nrg_ExternalCreditRatingNotRatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CounterpartyRiskByInvestmentGradeDomain_073e9234-7e77-461d-b8eb-8f792002ed92" xlink:to="loc_nrg_ExternalCreditRatingNotRatedMember_b2df3988-1c3e-405e-b7ad-6c820a75cfbf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AmountOfCreditExposureToSignificantPortionOfAllCounterparties_48239cc2-f886-4e3f-82fa-d137fc2ddabe" xlink:href="nrg-20231231.xsd#nrg_AmountOfCreditExposureToSignificantPortionOfAllCounterparties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_AmountOfCreditExposureToSignificantPortionOfAllCounterparties_48239cc2-f886-4e3f-82fa-d137fc2ddabe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CollateralHeldCashAndLettersOfCredit_ddb1c481-cc3c-450f-9eca-c8f66f6cf7cf" xlink:href="nrg-20231231.xsd#nrg_CollateralHeldCashAndLettersOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_CollateralHeldCashAndLettersOfCredit_ddb1c481-cc3c-450f-9eca-c8f66f6cf7cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NetCreditExposure_872b606f-02eb-4a7a-ba9b-936ca38aab4f" xlink:href="nrg-20231231.xsd#nrg_NetCreditExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_NetCreditExposure_872b606f-02eb-4a7a-ba9b-936ca38aab4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyCreditRiskExposurePercentageOfCreditRiskRollOff_dc781d5f-fada-457d-b2ef-d15ed9fdf03f" xlink:href="nrg-20231231.xsd#nrg_CounterpartyCreditRiskExposurePercentageOfCreditRiskRollOff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_CounterpartyCreditRiskExposurePercentageOfCreditRiskRollOff_dc781d5f-fada-457d-b2ef-d15ed9fdf03f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CreditDerivativeMaximumNetExposurePercentage_051f5199-f3b0-4818-a17b-7e59f57845b4" xlink:href="nrg-20231231.xsd#nrg_CreditDerivativeMaximumNetExposurePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_CreditDerivativeMaximumNetExposurePercentage_051f5199-f3b0-4818-a17b-7e59f57845b4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CounterpartyCreditRiskExposurePercentageThreshold_fb0e19e3-e705-4162-a936-cbac63ead0a4" xlink:href="nrg-20231231.xsd#nrg_CounterpartyCreditRiskExposurePercentageThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_CounterpartyCreditRiskExposurePercentageThreshold_fb0e19e3-e705-4162-a936-cbac63ead0a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterparties_aaa4fa5d-425a-48bc-813d-e0868f520056" xlink:href="nrg-20231231.xsd#nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterparties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterparties_aaa4fa5d-425a-48bc-813d-e0868f520056" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterpartiesPeriod_5b19fca2-5ec7-4990-8e10-319279bd270a" xlink:href="nrg-20231231.xsd#nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterpartiesPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_3b0f3eb5-1fef-49f5-a66c-ea7d6f16bbed" xlink:to="loc_nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterpartiesPeriod_5b19fca2-5ec7-4990-8e10-319279bd270a" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsRetailCustomerCreditRiskDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#FairValueofFinancialInstrumentsRetailCustomerCreditRiskDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/FairValueofFinancialInstrumentsRetailCustomerCreditRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_149301cb-4556-49da-8b9d-4f95fb2e2e4d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskTable_4f2bd823-f651-4fae-b800-a7d65436becc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueConcentrationOfRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_149301cb-4556-49da-8b9d-4f95fb2e2e4d" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskTable_4f2bd823-f651-4fae-b800-a7d65436becc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_7284d5f0-f6a5-45ca-aa0d-aac19c7e5b64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskTable_4f2bd823-f651-4fae-b800-a7d65436becc" xlink:to="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_7284d5f0-f6a5-45ca-aa0d-aac19c7e5b64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CatastrophicEventDomain_7284d5f0-f6a5-45ca-aa0d-aac19c7e5b64_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CatastrophicEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_7284d5f0-f6a5-45ca-aa0d-aac19c7e5b64" xlink:to="loc_us-gaap_CatastrophicEventDomain_7284d5f0-f6a5-45ca-aa0d-aac19c7e5b64_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CatastrophicEventDomain_d7f3d37d-46d6-4619-8a84-e2d6c91c22ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CatastrophicEventDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LiabilityForCatastropheClaimsByCatastrophicEventAxis_7284d5f0-f6a5-45ca-aa0d-aac19c7e5b64" xlink:to="loc_us-gaap_CatastrophicEventDomain_d7f3d37d-46d6-4619-8a84-e2d6c91c22ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WinterStormUriMember_d4c724e1-157a-41d4-8ef4-3b55cb75639b" xlink:href="nrg-20231231.xsd#nrg_WinterStormUriMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CatastrophicEventDomain_d7f3d37d-46d6-4619-8a84-e2d6c91c22ea" xlink:to="loc_nrg_WinterStormUriMember_d4c724e1-157a-41d4-8ef4-3b55cb75639b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_7951c747-9989-446a-8fcb-baa9131c799c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems_149301cb-4556-49da-8b9d-4f95fb2e2e4d" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_7951c747-9989-446a-8fcb-baa9131c799c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AccountingforDerivativeInstrumentsandHedgingActivitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_9685ab70-f3c3-4ac1-bca3-acde0714077b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_f916542d-2857-45cd-ad85-71c3f0336c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_9685ab70-f3c3-4ac1-bca3-acde0714077b" xlink:to="loc_us-gaap_DerivativeTable_f916542d-2857-45cd-ad85-71c3f0336c7e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_81343583-0d57-49d1-bd0a-bc354b740b3a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_f916542d-2857-45cd-ad85-71c3f0336c7e" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_81343583-0d57-49d1-bd0a-bc354b740b3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_81343583-0d57-49d1-bd0a-bc354b740b3a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_81343583-0d57-49d1-bd0a-bc354b740b3a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_81343583-0d57-49d1-bd0a-bc354b740b3a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_f43ff29d-4aa5-4e21-b6c1-1cb488f603e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_81343583-0d57-49d1-bd0a-bc354b740b3a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_f43ff29d-4aa5-4e21-b6c1-1cb488f603e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_be7aaa65-6169-405f-a72b-8bd24ce8b815" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f43ff29d-4aa5-4e21-b6c1-1cb488f603e8" xlink:to="loc_us-gaap_InterestRateSwapMember_be7aaa65-6169-405f-a72b-8bd24ce8b815" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_a35c8a24-93dd-4258-a382-8436038c30aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_f916542d-2857-45cd-ad85-71c3f0336c7e" xlink:to="loc_us-gaap_DebtInstrumentAxis_a35c8a24-93dd-4258-a382-8436038c30aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_a35c8a24-93dd-4258-a382-8436038c30aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_a35c8a24-93dd-4258-a382-8436038c30aa" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_a35c8a24-93dd-4258-a382-8436038c30aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_03c393c1-f5c7-4a95-95e5-635db3100db5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_a35c8a24-93dd-4258-a382-8436038c30aa" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_03c393c1-f5c7-4a95-95e5-635db3100db5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TermLoanFacilityMember_445d7586-d964-4cc1-9cc1-a1fb918ab7f9" xlink:href="nrg-20231231.xsd#nrg_TermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_03c393c1-f5c7-4a95-95e5-635db3100db5" xlink:to="loc_nrg_TermLoanFacilityMember_445d7586-d964-4cc1-9cc1-a1fb918ab7f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_d1a8007c-5429-4fd4-9ab6-de699de37d6f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_9685ab70-f3c3-4ac1-bca3-acde0714077b" xlink:to="loc_us-gaap_DerivativeNotionalAmount_d1a8007c-5429-4fd4-9ab6-de699de37d6f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesNetNotionalVolumeBuySellofOpenDerivativeTransactionsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AccountingforDerivativeInstrumentsandHedgingActivitiesNetNotionalVolumeBuySellofOpenDerivativeTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesNetNotionalVolumeBuySellofOpenDerivativeTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_7ff338c3-090e-468c-9cdb-3d0b14ac57f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_ab2df4c7-1933-457b-af9e-db82ec246877" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_7ff338c3-090e-468c-9cdb-3d0b14ac57f0" xlink:to="loc_us-gaap_DerivativeTable_ab2df4c7-1933-457b-af9e-db82ec246877" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_e92d43bb-04bb-4d36-b7fb-05878b72e257" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_ab2df4c7-1933-457b-af9e-db82ec246877" xlink:to="loc_us-gaap_PositionAxis_e92d43bb-04bb-4d36-b7fb-05878b72e257" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_e92d43bb-04bb-4d36-b7fb-05878b72e257_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_e92d43bb-04bb-4d36-b7fb-05878b72e257" xlink:to="loc_us-gaap_PositionDomain_e92d43bb-04bb-4d36-b7fb-05878b72e257_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_5492ca68-baf3-4aea-9fe8-14ea05315cb9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_e92d43bb-04bb-4d36-b7fb-05878b72e257" xlink:to="loc_us-gaap_PositionDomain_5492ca68-baf3-4aea-9fe8-14ea05315cb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_203114f4-2787-4e5f-b431-98033909c5f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_5492ca68-baf3-4aea-9fe8-14ea05315cb9" xlink:to="loc_us-gaap_LongMember_203114f4-2787-4e5f-b431-98033909c5f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_fe5976be-811c-47aa-832c-1c7c08225841" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_5492ca68-baf3-4aea-9fe8-14ea05315cb9" xlink:to="loc_us-gaap_ShortMember_fe5976be-811c-47aa-832c-1c7c08225841" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnderlyingAssetClassAxis_bc7f7881-ab89-496c-8d3a-fab30a93d9b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnderlyingAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_ab2df4c7-1933-457b-af9e-db82ec246877" xlink:to="loc_us-gaap_UnderlyingAssetClassAxis_bc7f7881-ab89-496c-8d3a-fab30a93d9b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnderlyingAssetClassDomain_bc7f7881-ab89-496c-8d3a-fab30a93d9b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnderlyingAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_UnderlyingAssetClassAxis_bc7f7881-ab89-496c-8d3a-fab30a93d9b6" xlink:to="loc_us-gaap_UnderlyingAssetClassDomain_bc7f7881-ab89-496c-8d3a-fab30a93d9b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnderlyingAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_UnderlyingAssetClassAxis_bc7f7881-ab89-496c-8d3a-fab30a93d9b6" xlink:to="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmissionsMember_b109d1f4-1165-4113-9439-305283938c91" xlink:href="nrg-20231231.xsd#nrg_EmissionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_EmissionsMember_b109d1f4-1165-4113-9439-305283938c91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RenewableEnergyCertificatesMember_7c6e0fd2-09bd-4d30-bc77-290a4abfc8d8" xlink:href="nrg-20231231.xsd#nrg_RenewableEnergyCertificatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_RenewableEnergyCertificatesMember_7c6e0fd2-09bd-4d30-bc77-290a4abfc8d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CoalMember_11b5adec-f31a-4f7d-8b9b-d6424d96ccc5" xlink:href="nrg-20231231.xsd#nrg_CoalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_CoalMember_11b5adec-f31a-4f7d-8b9b-d6424d96ccc5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NaturalGasMember_8504e8d1-1e2a-489a-9014-288f283b8334" xlink:href="nrg-20231231.xsd#nrg_NaturalGasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_NaturalGasMember_8504e8d1-1e2a-489a-9014-288f283b8334" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OilMember_3a1b24bd-c36f-40c7-942c-a774a56a30fd" xlink:href="nrg-20231231.xsd#nrg_OilMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_OilMember_3a1b24bd-c36f-40c7-942c-a774a56a30fd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PowerMember_7c3eab8f-1842-464b-999b-a0819bb8e9c6" xlink:href="nrg-20231231.xsd#nrg_PowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_PowerMember_7c3eab8f-1842-464b-999b-a0819bb8e9c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_InterestMember_6229cdc2-f9f2-428d-b7c3-2a0677082833" xlink:href="nrg-20231231.xsd#nrg_InterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_InterestMember_6229cdc2-f9f2-428d-b7c3-2a0677082833" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeMember_9002ab3d-4764-4250-b5ca-81fe5d737c5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignExchangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_us-gaap_ForeignExchangeMember_9002ab3d-4764-4250-b5ca-81fe5d737c5b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramMember_c27e8fa9-9954-4e75-94a9-cbfc8eb8e915" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnderlyingAssetClassDomain_23970d93-b0a8-4824-b71d-895e7b4ac53a" xlink:to="loc_nrg_ConsumerFinancingProgramMember_c27e8fa9-9954-4e75-94a9-cbfc8eb8e915" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_d62ec36a-2014-469b-a48f-e7f6a5dc781d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountMass"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7ff338c3-090e-468c-9cdb-3d0b14ac57f0" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_d62ec36a-2014-469b-a48f-e7f6a5dc781d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeNonmonetaryNotionalAmountOther_598377a4-e345-4fb4-918b-0d800349bb0a" xlink:href="nrg-20231231.xsd#nrg_DerivativeNonmonetaryNotionalAmountOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7ff338c3-090e-468c-9cdb-3d0b14ac57f0" xlink:to="loc_nrg_DerivativeNonmonetaryNotionalAmountOther_598377a4-e345-4fb4-918b-0d800349bb0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_b23fff20-4299-49a1-b7bf-e337645bcc81" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7ff338c3-090e-468c-9cdb-3d0b14ac57f0" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_b23fff20-4299-49a1-b7bf-e337645bcc81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_ad0affa8-668b-418e-8098-8801d84790e5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountVolume"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7ff338c3-090e-468c-9cdb-3d0b14ac57f0" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_ad0affa8-668b-418e-8098-8801d84790e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_b4957f3f-54d7-486b-a9bb-d7c386b6935b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7ff338c3-090e-468c-9cdb-3d0b14ac57f0" xlink:to="loc_us-gaap_DerivativeNotionalAmount_b4957f3f-54d7-486b-a9bb-d7c386b6935b" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesFairValueWithintheDerivativeInstrumentValuationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AccountingforDerivativeInstrumentsandHedgingActivitiesFairValueWithintheDerivativeInstrumentValuationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesFairValueWithintheDerivativeInstrumentValuationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_ca6b5149-1190-41c4-ad6a-7bd87de2336e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_2c927379-a6e6-419b-9a8a-1cff38af3b43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_ca6b5149-1190-41c4-ad6a-7bd87de2336e" xlink:to="loc_us-gaap_DerivativeTable_2c927379-a6e6-419b-9a8a-1cff38af3b43" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_1c8d7400-ecb8-46b0-a9fa-35d6ba359b5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2c927379-a6e6-419b-9a8a-1cff38af3b43" xlink:to="loc_us-gaap_HedgingDesignationAxis_1c8d7400-ecb8-46b0-a9fa-35d6ba359b5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_1c8d7400-ecb8-46b0-a9fa-35d6ba359b5c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_1c8d7400-ecb8-46b0-a9fa-35d6ba359b5c" xlink:to="loc_us-gaap_HedgingDesignationDomain_1c8d7400-ecb8-46b0-a9fa-35d6ba359b5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_e8c75f9e-e499-426b-8fa5-1cd99104ae1b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_1c8d7400-ecb8-46b0-a9fa-35d6ba359b5c" xlink:to="loc_us-gaap_HedgingDesignationDomain_e8c75f9e-e499-426b-8fa5-1cd99104ae1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_5c7f3127-75b6-4472-a2bd-690e784db211" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_e8c75f9e-e499-426b-8fa5-1cd99104ae1b" xlink:to="loc_us-gaap_NondesignatedMember_5c7f3127-75b6-4472-a2bd-690e784db211" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_f2adfe09-04d4-452e-8036-ac8e4f870b91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2c927379-a6e6-419b-9a8a-1cff38af3b43" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_f2adfe09-04d4-452e-8036-ac8e4f870b91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_f2adfe09-04d4-452e-8036-ac8e4f870b91_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_f2adfe09-04d4-452e-8036-ac8e4f870b91" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_f2adfe09-04d4-452e-8036-ac8e4f870b91_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_f2adfe09-04d4-452e-8036-ac8e4f870b91" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_InterestRateContractCurrentMember_d168154c-0113-4231-b8e4-e35307d7af67" xlink:href="nrg-20231231.xsd#nrg_InterestRateContractCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_InterestRateContractCurrentMember_d168154c-0113-4231-b8e4-e35307d7af67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_InterestRateContractNonCurrentMember_2b2097fe-dd97-4dd8-8a56-3eba8f9aa9a0" xlink:href="nrg-20231231.xsd#nrg_InterestRateContractNonCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_InterestRateContractNonCurrentMember_2b2097fe-dd97-4dd8-8a56-3eba8f9aa9a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ForeignExchangeContractCurrentMember_d48de26d-d4c6-4f21-be01-387a3a8e4532" xlink:href="nrg-20231231.xsd#nrg_ForeignExchangeContractCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_ForeignExchangeContractCurrentMember_d48de26d-d4c6-4f21-be01-387a3a8e4532" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ForeignExchangeContractNoncurrentMember_c13a774a-6314-46e6-8602-becdf6b83b76" xlink:href="nrg-20231231.xsd#nrg_ForeignExchangeContractNoncurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_ForeignExchangeContractNoncurrentMember_c13a774a-6314-46e6-8602-becdf6b83b76" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommodityContractCurrentMember_9b467db1-ee57-4dc7-837a-ffe747c3161d" xlink:href="nrg-20231231.xsd#nrg_CommodityContractCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_CommodityContractCurrentMember_9b467db1-ee57-4dc7-837a-ffe747c3161d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommodityContractNonCurrentMember_df188898-3d33-42c5-bdf2-6634cfc66d48" xlink:href="nrg-20231231.xsd#nrg_CommodityContractNonCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_CommodityContractNonCurrentMember_df188898-3d33-42c5-bdf2-6634cfc66d48" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramCurrentMember_debf9fd9-ee94-4c46-953b-dc1867d34fa2" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramCurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_ConsumerFinancingProgramCurrentMember_debf9fd9-ee94-4c46-953b-dc1867d34fa2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramNoncurrentMember_acdabb68-437f-44e2-ae72-eb4019a1ee25" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramNoncurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_cf93b36e-5734-4807-afdc-3c4f1b485ae2" xlink:to="loc_nrg_ConsumerFinancingProgramNoncurrentMember_acdabb68-437f-44e2-ae72-eb4019a1ee25" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_4c3d47d7-9685-4133-a9c6-cf6d1a4296cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ca6b5149-1190-41c4-ad6a-7bd87de2336e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_4c3d47d7-9685-4133-a9c6-cf6d1a4296cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_1a4da5d8-0eea-4a81-ab47-034ef0d3e295" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ca6b5149-1190-41c4-ad6a-7bd87de2336e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_1a4da5d8-0eea-4a81-ab47-034ef0d3e295" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesOffsettingofDerivativesbyCounterpartyMasterAgreementLevelandCollateralReceivedDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AccountingforDerivativeInstrumentsandHedgingActivitiesOffsettingofDerivativesbyCounterpartyMasterAgreementLevelandCollateralReceivedDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesOffsettingofDerivativesbyCounterpartyMasterAgreementLevelandCollateralReceivedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:href="nrg-20231231.xsd#nrg_OffsettingAssetsAndLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_2a0f406e-83ac-43a6-8cef-bf25848d24bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeTable_2a0f406e-83ac-43a6-8cef-bf25848d24bc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_a99d8bd0-94a9-4a39-90f8-3cdc2f961d7c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2a0f406e-83ac-43a6-8cef-bf25848d24bc" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_a99d8bd0-94a9-4a39-90f8-3cdc2f961d7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a99d8bd0-94a9-4a39-90f8-3cdc2f961d7c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a99d8bd0-94a9-4a39-90f8-3cdc2f961d7c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a99d8bd0-94a9-4a39-90f8-3cdc2f961d7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ca5ec961-9fa4-4ff8-a4cd-89f1178c0ab2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a99d8bd0-94a9-4a39-90f8-3cdc2f961d7c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ca5ec961-9fa4-4ff8-a4cd-89f1178c0ab2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_b2e36851-2395-4111-a13b-78e2e7b0b991" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_ca5ec961-9fa4-4ff8-a4cd-89f1178c0ab2" xlink:to="loc_us-gaap_InterestRateContractMember_b2e36851-2395-4111-a13b-78e2e7b0b991" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_6a33111a-22cd-4e52-b215-e469bd98d140" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_ca5ec961-9fa4-4ff8-a4cd-89f1178c0ab2" xlink:to="loc_us-gaap_ForeignExchangeContractMember_6a33111a-22cd-4e52-b215-e469bd98d140" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_a4c7533d-b5ce-427d-93a5-443089ef80d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_ca5ec961-9fa4-4ff8-a4cd-89f1178c0ab2" xlink:to="loc_us-gaap_CommodityContractMember_a4c7533d-b5ce-427d-93a5-443089ef80d7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramMember_ca0904e7-7d54-4ad8-b4d6-a137e668e6da" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_ca5ec961-9fa4-4ff8-a4cd-89f1178c0ab2" xlink:to="loc_nrg_ConsumerFinancingProgramMember_ca0904e7-7d54-4ad8-b4d6-a137e668e6da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_f8ba552b-81fb-457e-90f6-193769625041" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_f8ba552b-81fb-457e-90f6-193769625041" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiability_75999d2e-f7bf-437a-a243-b65a04e436b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetFairValueGrossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiability_75999d2e-f7bf-437a-a243-b65a04e436b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralObligationToReturnCash_f7972d09-cd69-4d18-b0ff-f1027f2f0f08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeCollateralObligationToReturnCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeCollateralObligationToReturnCash_f7972d09-cd69-4d18-b0ff-f1027f2f0f08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_ff0d6cda-6515-4971-862a-9ed061974fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral_ff0d6cda-6515-4971-862a-9ed061974fb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_120dab02-0d82-41d0-a77d-2d419fcc8497" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_120dab02-0d82-41d0-a77d-2d419fcc8497" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_c48e2ca0-a4be-47bb-9e1a-730e0c788ce5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAsset_c48e2ca0-a4be-47bb-9e1a-730e0c788ce5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralRightToReclaimCash_c120f7d0-e2b9-492d-bde5-98bb98f168ad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeCollateralRightToReclaimCash_c120f7d0-e2b9-492d-bde5-98bb98f168ad" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_9758caef-b8a3-43b8-8174-6ae69e60323f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral_9758caef-b8a3-43b8-8174-6ae69e60323f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FairValueofGrossDerivativeAssetsLiabilitiesNet_08d430f7-d908-49ee-ae8e-6d65c5d47699" xlink:href="nrg-20231231.xsd#nrg_FairValueofGrossDerivativeAssetsLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_nrg_FairValueofGrossDerivativeAssetsLiabilitiesNet_08d430f7-d908-49ee-ae8e-6d65c5d47699" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeAssetFairValueGrossLiabilityNetOfDerivativeLiabilityFairValueGrossAsset_22885c04-e91b-4e3c-9071-20c73f5ac505" xlink:href="nrg-20231231.xsd#nrg_DerivativeAssetFairValueGrossLiabilityNetOfDerivativeLiabilityFairValueGrossAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_nrg_DerivativeAssetFairValueGrossLiabilityNetOfDerivativeLiabilityFairValueGrossAsset_22885c04-e91b-4e3c-9071-20c73f5ac505" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeCollateralObligationToReturnCashNetOfDerivativeCollateralRightToReclaimCash_48e6f644-d729-4912-aac2-be9c2ebbb922" xlink:href="nrg-20231231.xsd#nrg_DerivativeCollateralObligationToReturnCashNetOfDerivativeCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_nrg_DerivativeCollateralObligationToReturnCashNetOfDerivativeCollateralRightToReclaimCash_48e6f644-d729-4912-aac2-be9c2ebbb922" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral_f09536b4-3fb4-40fc-a821-923ec65cc358" xlink:href="nrg-20231231.xsd#nrg_DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_OffsettingAssetsAndLiabilitiesLineItems_0f739963-2e09-47e4-b3fb-b2dc53aa99b3" xlink:to="loc_nrg_DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral_f09536b4-3fb4-40fc-a821-923ec65cc358" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesPretaxEffectsofEconomicHedgesnotDesignatedasCashFlowHedgesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AccountingforDerivativeInstrumentsandHedgingActivitiesPretaxEffectsofEconomicHedgesnotDesignatedasCashFlowHedgesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AccountingforDerivativeInstrumentsandHedgingActivitiesPretaxEffectsofEconomicHedgesnotDesignatedasCashFlowHedgesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_a833108d-fe6e-4913-82c8-66bca1b4f086" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_b211d558-b52d-44d3-84f7-bd266fdb720c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_a833108d-fe6e-4913-82c8-66bca1b4f086" xlink:to="loc_us-gaap_DerivativeTable_b211d558-b52d-44d3-84f7-bd266fdb720c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_a5bad668-a876-405b-8658-af4f406e12e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_b211d558-b52d-44d3-84f7-bd266fdb720c" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_a5bad668-a876-405b-8658-af4f406e12e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a5bad668-a876-405b-8658-af4f406e12e0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a5bad668-a876-405b-8658-af4f406e12e0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a5bad668-a876-405b-8658-af4f406e12e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_95ba2eb7-4feb-4ed7-a590-6b2eb5f235f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a5bad668-a876-405b-8658-af4f406e12e0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_95ba2eb7-4feb-4ed7-a590-6b2eb5f235f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_50e2d002-0fa7-48da-b1ae-002145e64535" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_95ba2eb7-4feb-4ed7-a590-6b2eb5f235f3" xlink:to="loc_us-gaap_InterestRateContractMember_50e2d002-0fa7-48da-b1ae-002145e64535" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_fb3f2b70-c108-4788-919d-981949ed144a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_95ba2eb7-4feb-4ed7-a590-6b2eb5f235f3" xlink:to="loc_us-gaap_CommodityContractMember_fb3f2b70-c108-4788-919d-981949ed144a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_34b8e6a4-7739-45fe-bc5a-b5bf87a2e198" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_95ba2eb7-4feb-4ed7-a590-6b2eb5f235f3" xlink:to="loc_us-gaap_ForeignExchangeContractMember_34b8e6a4-7739-45fe-bc5a-b5bf87a2e198" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommodityAndForeignExchangeContractsMember_0e2504f3-b5bd-47a0-8db4-c489b87cdc71" xlink:href="nrg-20231231.xsd#nrg_CommodityAndForeignExchangeContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_95ba2eb7-4feb-4ed7-a590-6b2eb5f235f3" xlink:to="loc_nrg_CommodityAndForeignExchangeContractsMember_0e2504f3-b5bd-47a0-8db4-c489b87cdc71" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConsumerFinancingProgramMember_5f72f68e-ba07-4bfb-a81d-4b36ccaca85c" xlink:href="nrg-20231231.xsd#nrg_ConsumerFinancingProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_95ba2eb7-4feb-4ed7-a590-6b2eb5f235f3" xlink:to="loc_nrg_ConsumerFinancingProgramMember_5f72f68e-ba07-4bfb-a81d-4b36ccaca85c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_528405de-5b84-44fd-bdd9-fce5b94b9827" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_b211d558-b52d-44d3-84f7-bd266fdb720c" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_528405de-5b84-44fd-bdd9-fce5b94b9827" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_528405de-5b84-44fd-bdd9-fce5b94b9827_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_528405de-5b84-44fd-bdd9-fce5b94b9827" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_528405de-5b84-44fd-bdd9-fce5b94b9827_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_bf189262-ef70-4600-938e-7ad6704a610f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_528405de-5b84-44fd-bdd9-fce5b94b9827" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_bf189262-ef70-4600-938e-7ad6704a610f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesMember_afd6afd3-97d6-492f-bf3c-c194fa40ecff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_bf189262-ef70-4600-938e-7ad6704a610f" xlink:to="loc_us-gaap_SalesMember_afd6afd3-97d6-492f-bf3c-c194fa40ecff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_c9209f61-4105-43da-9936-38c7595d3b76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_bf189262-ef70-4600-938e-7ad6704a610f" xlink:to="loc_us-gaap_CostOfSalesMember_c9209f61-4105-43da-9936-38c7595d3b76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_23856696-aa8e-465e-995c-a1de9cde8bf9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_b211d558-b52d-44d3-84f7-bd266fdb720c" xlink:to="loc_us-gaap_HedgingDesignationAxis_23856696-aa8e-465e-995c-a1de9cde8bf9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_23856696-aa8e-465e-995c-a1de9cde8bf9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_23856696-aa8e-465e-995c-a1de9cde8bf9" xlink:to="loc_us-gaap_HedgingDesignationDomain_23856696-aa8e-465e-995c-a1de9cde8bf9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_e62dfc3e-a35f-4b98-ab53-9735374c83b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_23856696-aa8e-465e-995c-a1de9cde8bf9" xlink:to="loc_us-gaap_HedgingDesignationDomain_e62dfc3e-a35f-4b98-ab53-9735374c83b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember_70f938c9-d177-4751-a920-ca3d5e7c723c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_e62dfc3e-a35f-4b98-ab53-9735374c83b6" xlink:to="loc_us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember_70f938c9-d177-4751-a920-ca3d5e7c723c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditDerivativesByContractTypeAxis_79976e32-f785-44e5-85e2-54b060ef74e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditDerivativesByContractTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_b211d558-b52d-44d3-84f7-bd266fdb720c" xlink:to="loc_us-gaap_CreditDerivativesByContractTypeAxis_79976e32-f785-44e5-85e2-54b060ef74e6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditDerivativesContractTypeDomain_79976e32-f785-44e5-85e2-54b060ef74e6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditDerivativesContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditDerivativesByContractTypeAxis_79976e32-f785-44e5-85e2-54b060ef74e6" xlink:to="loc_us-gaap_CreditDerivativesContractTypeDomain_79976e32-f785-44e5-85e2-54b060ef74e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditDerivativesContractTypeDomain_626da0de-b0c6-4f39-9d6b-d08b499d6970" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditDerivativesContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditDerivativesByContractTypeAxis_79976e32-f785-44e5-85e2-54b060ef74e6" xlink:to="loc_us-gaap_CreditDerivativesContractTypeDomain_626da0de-b0c6-4f39-9d6b-d08b499d6970" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AdequateAssuranceClausesMember_eea078e1-1863-45de-b08c-1bea4c153c10" xlink:href="nrg-20231231.xsd#nrg_AdequateAssuranceClausesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditDerivativesContractTypeDomain_626da0de-b0c6-4f39-9d6b-d08b499d6970" xlink:to="loc_nrg_AdequateAssuranceClausesMember_eea078e1-1863-45de-b08c-1bea4c153c10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:href="nrg-20231231.xsd#nrg_UnrealizedMarkToMarketResultsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_a833108d-fe6e-4913-82c8-66bca1b4f086" xlink:to="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ReversalPreviouslyRecognizedUnrealizedGainsLossesSettledPositionsEconomicHedges_70fc1573-5339-446a-8ddf-f89b32723da4" xlink:href="nrg-20231231.xsd#nrg_ReversalPreviouslyRecognizedUnrealizedGainsLossesSettledPositionsEconomicHedges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_nrg_ReversalPreviouslyRecognizedUnrealizedGainsLossesSettledPositionsEconomicHedges_70fc1573-5339-446a-8ddf-f89b32723da4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ReversalPreviouslyRecognizedUnrealizedGainsLossesAcquiredasPartofAcquisitionEconomicHedges_34d590c8-d0f8-4670-bd8b-8cfff5c20c00" xlink:href="nrg-20231231.xsd#nrg_ReversalPreviouslyRecognizedUnrealizedGainsLossesAcquiredasPartofAcquisitionEconomicHedges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_nrg_ReversalPreviouslyRecognizedUnrealizedGainsLossesAcquiredasPartofAcquisitionEconomicHedges_34d590c8-d0f8-4670-bd8b-8cfff5c20c00" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_843e0ae4-0681-40ca-a9fe-28c4e38595f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_843e0ae4-0681-40ca-a9fe-28c4e38595f4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_UnrealizedGainLossOnDerivativesMarkToMarketEconomicHedgingActivities_0d0001f2-ce45-4672-b76d-e9889d84d8e4" xlink:href="nrg-20231231.xsd#nrg_UnrealizedGainLossOnDerivativesMarkToMarketEconomicHedgingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_nrg_UnrealizedGainLossOnDerivativesMarkToMarketEconomicHedgingActivities_0d0001f2-ce45-4672-b76d-e9889d84d8e4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ReversalPreviouslyUnrecognizedUnrealizedGainsLossesSettledPositionsTradingActivity_81c29cac-bd13-4a9a-89bf-b67201aa8b1d" xlink:href="nrg-20231231.xsd#nrg_ReversalPreviouslyUnrecognizedUnrealizedGainsLossesSettledPositionsTradingActivity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_nrg_ReversalPreviouslyUnrecognizedUnrealizedGainsLossesSettledPositionsTradingActivity_81c29cac-bd13-4a9a-89bf-b67201aa8b1d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ReversalOfAcquiredGainPositionsRelatedToTradingActivity_a3cb6c64-ddff-44a1-b224-a21112b45445" xlink:href="nrg-20231231.xsd#nrg_ReversalOfAcquiredGainPositionsRelatedToTradingActivity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_nrg_ReversalOfAcquiredGainPositionsRelatedToTradingActivity_a3cb6c64-ddff-44a1-b224-a21112b45445" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DerivativeUnrealizedGainsOnOpenPositionsRelatedToTradingActivityNet_a502071b-4cf3-4d80-a081-56ae95484a2a" xlink:href="nrg-20231231.xsd#nrg_DerivativeUnrealizedGainsOnOpenPositionsRelatedToTradingActivityNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_nrg_DerivativeUnrealizedGainsOnOpenPositionsRelatedToTradingActivityNet_a502071b-4cf3-4d80-a081-56ae95484a2a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_UnrealizedGainLossonDerivativesMarkToMarketTradingActivities_b78adb07-b8dc-4ecc-980e-5b07e36c26e2" xlink:href="nrg-20231231.xsd#nrg_UnrealizedGainLossonDerivativesMarkToMarketTradingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_nrg_UnrealizedGainLossonDerivativesMarkToMarketTradingActivities_b78adb07-b8dc-4ecc-980e-5b07e36c26e2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivativesAndCommodityContracts_668a3a1d-36f5-42be-957c-1ba89cd7b520" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrealizedGainLossOnDerivativesAndCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivativesAndCommodityContracts_668a3a1d-36f5-42be-957c-1ba89cd7b520" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_3c7125d5-c910-4a89-8f71-f7d0ee55c903" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_UnrealizedMarkToMarketResultsAbstract_67d77756-dc22-47e8-9539-3f11c6c3c5ae" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_3c7125d5-c910-4a89-8f71-f7d0ee55c903" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CreditRiskRelatedContingentFeaturesAbstract_99a2391f-7f06-4edb-8a09-47e2db373e58" xlink:href="nrg-20231231.xsd#nrg_CreditRiskRelatedContingentFeaturesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_a833108d-fe6e-4913-82c8-66bca1b4f086" xlink:to="loc_nrg_CreditRiskRelatedContingentFeaturesAbstract_99a2391f-7f06-4edb-8a09-47e2db373e58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnEnergyContracts_b5876e34-ee64-4ec6-b3c6-e62424fdd055" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrealizedGainLossOnEnergyContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CreditRiskRelatedContingentFeaturesAbstract_99a2391f-7f06-4edb-8a09-47e2db373e58" xlink:to="loc_us-gaap_UnrealizedGainLossOnEnergyContracts_b5876e34-ee64-4ec6-b3c6-e62424fdd055" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralAlreadyPostedAggregateFairValue_965a5a6b-14ce-461b-b97f-27907f05e1db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CollateralAlreadyPostedAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CreditRiskRelatedContingentFeaturesAbstract_99a2391f-7f06-4edb-8a09-47e2db373e58" xlink:to="loc_us-gaap_CollateralAlreadyPostedAggregateFairValue_965a5a6b-14ce-461b-b97f-27907f05e1db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNetLiabilityPositionAggregateFairValue_c836d55b-ccf7-4678-95da-574082fd2823" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNetLiabilityPositionAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CreditRiskRelatedContingentFeaturesAbstract_99a2391f-7f06-4edb-8a09-47e2db373e58" xlink:to="loc_us-gaap_DerivativeNetLiabilityPositionAggregateFairValue_c836d55b-ccf7-4678-95da-574082fd2823" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalCollateralAggregateFairValue_063a90ce-43a8-43b1-b23f-604d5bddfcfe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalCollateralAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CreditRiskRelatedContingentFeaturesAbstract_99a2391f-7f06-4edb-8a09-47e2db373e58" xlink:to="loc_us-gaap_AdditionalCollateralAggregateFairValue_063a90ce-43a8-43b1-b23f-604d5bddfcfe" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/NuclearDecommissioningTrustFundSummaryofAggregateFairValuesandRealizedGainsandLossesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#NuclearDecommissioningTrustFundSummaryofAggregateFairValuesandRealizedGainsandLossesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/NuclearDecommissioningTrustFundSummaryofAggregateFairValuesandRealizedGainsandLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2880bdac-0139-47b5-b1a9-79118153583f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_26c19996-4126-44dd-81a4-9f8746b5467a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2880bdac-0139-47b5-b1a9-79118153583f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_26c19996-4126-44dd-81a4-9f8746b5467a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantAxis_377b3ecf-46a6-4850-ac12-c6d78adc7421" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_26c19996-4126-44dd-81a4-9f8746b5467a" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantAxis_377b3ecf-46a6-4850-ac12-c6d78adc7421" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_377b3ecf-46a6-4850-ac12-c6d78adc7421_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_377b3ecf-46a6-4850-ac12-c6d78adc7421" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_377b3ecf-46a6-4850-ac12-c6d78adc7421_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_097dc9f1-14b9-44cb-b56f-8f9b2e47e30c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_377b3ecf-46a6-4850-ac12-c6d78adc7421" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_097dc9f1-14b9-44cb-b56f-8f9b2e47e30c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectUnits1And2Member_25a6e737-be08-4bc1-9802-1b9809a75c70" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectUnits1And2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantDomain_097dc9f1-14b9-44cb-b56f-8f9b2e47e30c" xlink:to="loc_nrg_SouthTexasProjectUnits1And2Member_25a6e737-be08-4bc1-9802-1b9809a75c70" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_f5b1af2d-9c70-4ed6-b7fb-35e2efcdd78d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_26c19996-4126-44dd-81a4-9f8746b5467a" xlink:to="loc_us-gaap_FinancialInstrumentAxis_f5b1af2d-9c70-4ed6-b7fb-35e2efcdd78d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f5b1af2d-9c70-4ed6-b7fb-35e2efcdd78d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_f5b1af2d-9c70-4ed6-b7fb-35e2efcdd78d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_f5b1af2d-9c70-4ed6-b7fb-35e2efcdd78d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_f5b1af2d-9c70-4ed6-b7fb-35e2efcdd78d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_46e60fec-9c02-4a9b-98eb-ddf2ba99764d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_46e60fec-9c02-4a9b-98eb-ddf2ba99764d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_15f4878a-fdc6-49ef-b886-e825043bda4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_15f4878a-fdc6-49ef-b886-e825043bda4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_ef702d10-b4e6-42a0-8979-2fe809a2c764" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:to="loc_us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_ef702d10-b4e6-42a0-8979-2fe809a2c764" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_ca7ecf6f-b7ba-464a-9413-019acef8c333" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_ca7ecf6f-b7ba-464a-9413-019acef8c333" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_97453ed3-0848-4952-860c-922f7cb0fdf5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_97453ed3-0848-4952-860c-922f7cb0fdf5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_034a494c-f6f4-4868-ad53-d34c9b5266aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:to="loc_us-gaap_EquitySecuritiesMember_034a494c-f6f4-4868-ad53-d34c9b5266aa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_ccd775c0-1e9e-4cd4-881c-9350c776f09d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3e182a40-6a88-493c-be92-3b5e57a62899" xlink:to="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_ccd775c0-1e9e-4cd4-881c-9350c776f09d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare_7f98d1b7-c9f5-4a89-9cba-2d2fddffcca1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2880bdac-0139-47b5-b1a9-79118153583f" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare_7f98d1b7-c9f5-4a89-9cba-2d2fddffcca1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_cd77a3bf-7ffc-4152-91cc-4b863aa979ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2880bdac-0139-47b5-b1a9-79118153583f" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_cd77a3bf-7ffc-4152-91cc-4b863aa979ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DecommissioningFundInvestmentsUnrealizedGains_304dc1f1-558a-4cca-9826-de20b5041d86" xlink:href="nrg-20231231.xsd#nrg_DecommissioningFundInvestmentsUnrealizedGains"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2880bdac-0139-47b5-b1a9-79118153583f" xlink:to="loc_nrg_DecommissioningFundInvestmentsUnrealizedGains_304dc1f1-558a-4cca-9826-de20b5041d86" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DecommissioningFundInvestmentsUnrealizedLoss_5fd08498-c2c9-48cc-8f3b-7aab0b378159" xlink:href="nrg-20231231.xsd#nrg_DecommissioningFundInvestmentsUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2880bdac-0139-47b5-b1a9-79118153583f" xlink:to="loc_nrg_DecommissioningFundInvestmentsUnrealizedLoss_5fd08498-c2c9-48cc-8f3b-7aab0b378159" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DecommissioningTrustAssetsWeightedAverageMaturityPeriod_b3a997ad-3b22-42a7-b1ce-5e1eaedeebd6" xlink:href="nrg-20231231.xsd#nrg_DecommissioningTrustAssetsWeightedAverageMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_2880bdac-0139-47b5-b1a9-79118153583f" xlink:to="loc_nrg_DecommissioningTrustAssetsWeightedAverageMaturityPeriod_b3a997ad-3b22-42a7-b1ce-5e1eaedeebd6" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/PropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#PropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/PropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e39817-5135-48cd-8317-cbaa198ae7a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_dbefece9-e860-4c9f-8311-80a8056adee2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e39817-5135-48cd-8317-cbaa198ae7a8" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_dbefece9-e860-4c9f-8311-80a8056adee2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90b60441-ecc0-4a1c-9332-2c4b088ca8f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_dbefece9-e860-4c9f-8311-80a8056adee2" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90b60441-ecc0-4a1c-9332-2c4b088ca8f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_90b60441-ecc0-4a1c-9332-2c4b088ca8f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90b60441-ecc0-4a1c-9332-2c4b088ca8f9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_90b60441-ecc0-4a1c-9332-2c4b088ca8f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_860077a7-6857-43ac-b208-4ccfce091174" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_90b60441-ecc0-4a1c-9332-2c4b088ca8f9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_860077a7-6857-43ac-b208-4ccfce091174" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FacilitiesAndEquipmentMember_83a4a373-45ec-4f90-8cd7-38b43aa0d7ce" xlink:href="nrg-20231231.xsd#nrg_FacilitiesAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_860077a7-6857-43ac-b208-4ccfce091174" xlink:to="loc_nrg_FacilitiesAndEquipmentMember_83a4a373-45ec-4f90-8cd7-38b43aa0d7ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndLandImprovementsMember_589f875e-97a6-455c-9c19-eaf76128cd52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LandAndLandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_860077a7-6857-43ac-b208-4ccfce091174" xlink:to="loc_us-gaap_LandAndLandImprovementsMember_589f875e-97a6-455c-9c19-eaf76128cd52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelMember_2be7196a-4a9d-4701-92dc-f1d4bdd84b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_860077a7-6857-43ac-b208-4ccfce091174" xlink:to="loc_us-gaap_NuclearFuelMember_2be7196a-4a9d-4701-92dc-f1d4bdd84b9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OfficeEquipmentMember_f40106fb-aca7-4d29-a1ef-6e1dee704b5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OfficeEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_860077a7-6857-43ac-b208-4ccfce091174" xlink:to="loc_us-gaap_OfficeEquipmentMember_f40106fb-aca7-4d29-a1ef-6e1dee704b5d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_b7ad407c-917f-45ab-956a-ee51d77da514" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_860077a7-6857-43ac-b208-4ccfce091174" xlink:to="loc_us-gaap_ConstructionInProgressMember_b7ad407c-917f-45ab-956a-ee51d77da514" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_d34f86fd-0d96-4fd7-ba51-e0afde94cdf6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_dbefece9-e860-4c9f-8311-80a8056adee2" xlink:to="loc_srt_RangeAxis_d34f86fd-0d96-4fd7-ba51-e0afde94cdf6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d34f86fd-0d96-4fd7-ba51-e0afde94cdf6_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_d34f86fd-0d96-4fd7-ba51-e0afde94cdf6" xlink:to="loc_srt_RangeMember_d34f86fd-0d96-4fd7-ba51-e0afde94cdf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5aa59980-4749-4ba9-86a0-0f1475f4a73f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_d34f86fd-0d96-4fd7-ba51-e0afde94cdf6" xlink:to="loc_srt_RangeMember_5aa59980-4749-4ba9-86a0-0f1475f4a73f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_d8958f3a-bdcd-412f-9c23-4588d5894f4c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5aa59980-4749-4ba9-86a0-0f1475f4a73f" xlink:to="loc_srt_MinimumMember_d8958f3a-bdcd-412f-9c23-4588d5894f4c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_51c36258-9372-4121-9229-afeb2c97fc77" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5aa59980-4749-4ba9-86a0-0f1475f4a73f" xlink:to="loc_srt_MaximumMember_51c36258-9372-4121-9229-afeb2c97fc77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_c48b7363-cf86-463e-8274-f7137834af12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e39817-5135-48cd-8317-cbaa198ae7a8" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService_c48b7363-cf86-463e-8274-f7137834af12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_ca0afdb4-8d40-4623-9aa1-90ad0fd32447" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e39817-5135-48cd-8317-cbaa198ae7a8" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation_ca0afdb4-8d40-4623-9aa1-90ad0fd32447" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_f93e9b0b-f135-4404-b49b-8cb57ddc8964" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e39817-5135-48cd-8317-cbaa198ae7a8" xlink:to="loc_us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet_f93e9b0b-f135-4404-b49b-8cb57ddc8964" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_0164ebe2-cd3f-4d6a-a648-afa89c7fa547" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e39817-5135-48cd-8317-cbaa198ae7a8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_0164ebe2-cd3f-4d6a-a648-afa89c7fa547" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_322903fb-68ac-41fa-9ddf-fdbb3d458df7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b4e39817-5135-48cd-8317-cbaa198ae7a8" xlink:to="loc_us-gaap_Depreciation_322903fb-68ac-41fa-9ddf-fdbb3d458df7" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AssetImpairmentsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AssetImpairmentsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AssetImpairmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_7a6fcce6-148b-471b-9411-2da71dffd54b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable_afaa092b-8e28-4e23-ba86-a16d9b88eb3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_7a6fcce6-148b-471b-9411-2da71dffd54b" xlink:to="loc_us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable_afaa092b-8e28-4e23-ba86-a16d9b88eb3c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_bb10be9c-bc0f-4719-93e4-1b65dbd5f007" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable_afaa092b-8e28-4e23-ba86-a16d9b88eb3c" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_bb10be9c-bc0f-4719-93e4-1b65dbd5f007" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_bb10be9c-bc0f-4719-93e4-1b65dbd5f007_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_bb10be9c-bc0f-4719-93e4-1b65dbd5f007" xlink:to="loc_us-gaap_SegmentDomain_bb10be9c-bc0f-4719-93e4-1b65dbd5f007_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_46226f4a-7033-491d-841e-f5b9beba2aea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_bb10be9c-bc0f-4719-93e4-1b65dbd5f007" xlink:to="loc_us-gaap_SegmentDomain_46226f4a-7033-491d-841e-f5b9beba2aea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EastSegmentMember_5af169cb-310d-461e-b4a8-65599135fea6" xlink:href="nrg-20231231.xsd#nrg_EastSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_46226f4a-7033-491d-841e-f5b9beba2aea" xlink:to="loc_nrg_EastSegmentMember_5af169cb-310d-461e-b4a8-65599135fea6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WestServicesAndOtherSegmentMember_6cbd7219-51b7-44a0-b03c-9bb6a1c79159" xlink:href="nrg-20231231.xsd#nrg_WestServicesAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_46226f4a-7033-491d-841e-f5b9beba2aea" xlink:to="loc_nrg_WestServicesAndOtherSegmentMember_6cbd7219-51b7-44a0-b03c-9bb6a1c79159" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TexasSegmentMember_a63a0c99-5a31-4d5b-a2fe-ab78c3748fef" xlink:href="nrg-20231231.xsd#nrg_TexasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_46226f4a-7033-491d-841e-f5b9beba2aea" xlink:to="loc_nrg_TexasSegmentMember_a63a0c99-5a31-4d5b-a2fe-ab78c3748fef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aac77aa8-9dad-4a8e-b62b-1a70e7dc9529" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable_afaa092b-8e28-4e23-ba86-a16d9b88eb3c" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aac77aa8-9dad-4a8e-b62b-1a70e7dc9529" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_aac77aa8-9dad-4a8e-b62b-1a70e7dc9529_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aac77aa8-9dad-4a8e-b62b-1a70e7dc9529" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_aac77aa8-9dad-4a8e-b62b-1a70e7dc9529_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_0f0c02e4-fa2b-4356-a2f2-1a9f8f395e06" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aac77aa8-9dad-4a8e-b62b-1a70e7dc9529" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_0f0c02e4-fa2b-4356-a2f2-1a9f8f395e06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GladstonePowerStationMember_05474139-5899-4e2a-be7e-3020b159806a" xlink:href="nrg-20231231.xsd#nrg_GladstonePowerStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_0f0c02e4-fa2b-4356-a2f2-1a9f8f395e06" xlink:to="loc_nrg_GladstonePowerStationMember_05474139-5899-4e2a-be7e-3020b159806a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LeasedAssetsPowertonFacilityAndUnits7And8OfTheJolietFacilityMember_c389c6b0-a8a5-4a3a-9e1d-4dfb484d6dc6" xlink:href="nrg-20231231.xsd#nrg_LeasedAssetsPowertonFacilityAndUnits7And8OfTheJolietFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_0f0c02e4-fa2b-4356-a2f2-1a9f8f395e06" xlink:to="loc_nrg_LeasedAssetsPowertonFacilityAndUnits7And8OfTheJolietFacilityMember_c389c6b0-a8a5-4a3a-9e1d-4dfb484d6dc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PJMCoalGeneratingAssetsMember_fa4b8225-14c2-4b39-bc5c-be939b379790" xlink:href="nrg-20231231.xsd#nrg_PJMCoalGeneratingAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_0f0c02e4-fa2b-4356-a2f2-1a9f8f395e06" xlink:to="loc_nrg_PJMCoalGeneratingAssetsMember_fa4b8225-14c2-4b39-bc5c-be939b379790" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_e003f03b-c6f4-4ce4-b9d5-8b964606cf73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_7a6fcce6-148b-471b-9411-2da71dffd54b" xlink:to="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_e003f03b-c6f4-4ce4-b9d5-8b964606cf73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_b1b59f2c-4dbe-4465-8060-4c7b9e30cfd0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_7a6fcce6-148b-471b-9411-2da71dffd54b" xlink:to="loc_us-gaap_AssetImpairmentCharges_b1b59f2c-4dbe-4465-8060-4c7b9e30cfd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_cceca13f-9100-44e3-bf09-60adb7186497" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_7a6fcce6-148b-471b-9411-2da71dffd54b" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_cceca13f-9100-44e3-bf09-60adb7186497" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesChangesinGoodwillDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#GoodwillandOtherIntangiblesChangesinGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesChangesinGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_17689b02-ffb3-4998-b328-919811e37ef9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_ec682bd6-ce5c-4b71-9404-64f3be0e130b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_17689b02-ffb3-4998-b328-919811e37ef9" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_ec682bd6-ce5c-4b71-9404-64f3be0e130b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_99916da4-3d0d-41a4-86f9-eaa51bf728ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_ec682bd6-ce5c-4b71-9404-64f3be0e130b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_99916da4-3d0d-41a4-86f9-eaa51bf728ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_99916da4-3d0d-41a4-86f9-eaa51bf728ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_99916da4-3d0d-41a4-86f9-eaa51bf728ca" xlink:to="loc_us-gaap_SegmentDomain_99916da4-3d0d-41a4-86f9-eaa51bf728ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0a27364a-8696-42a5-9703-ddbd49d3401e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_99916da4-3d0d-41a4-86f9-eaa51bf728ca" xlink:to="loc_us-gaap_SegmentDomain_0a27364a-8696-42a5-9703-ddbd49d3401e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TexasSegmentMember_135025ef-4f62-492e-be6c-a6ed2de6914d" xlink:href="nrg-20231231.xsd#nrg_TexasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0a27364a-8696-42a5-9703-ddbd49d3401e" xlink:to="loc_nrg_TexasSegmentMember_135025ef-4f62-492e-be6c-a6ed2de6914d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EastSegmentMember_2acb8613-6d12-4f83-907a-78394e98a3fc" xlink:href="nrg-20231231.xsd#nrg_EastSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0a27364a-8696-42a5-9703-ddbd49d3401e" xlink:to="loc_nrg_EastSegmentMember_2acb8613-6d12-4f83-907a-78394e98a3fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WestAndOtherSegmentMember_24b6076a-e491-4700-91a4-169ae535bf01" xlink:href="nrg-20231231.xsd#nrg_WestAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0a27364a-8696-42a5-9703-ddbd49d3401e" xlink:to="loc_nrg_WestAndOtherSegmentMember_24b6076a-e491-4700-91a4-169ae535bf01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSmartHomeIncMember_4325e23a-a43c-4fc2-aef0-295b4bfc91a3" xlink:href="nrg-20231231.xsd#nrg_VivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0a27364a-8696-42a5-9703-ddbd49d3401e" xlink:to="loc_nrg_VivintSmartHomeIncMember_4325e23a-a43c-4fc2-aef0-295b4bfc91a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_594c66e7-5758-495b-9e28-9f22c7b44feb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_17689b02-ffb3-4998-b328-919811e37ef9" xlink:to="loc_us-gaap_GoodwillRollForward_594c66e7-5758-495b-9e28-9f22c7b44feb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_8b086163-f008-4d9f-9065-52433ab280d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_594c66e7-5758-495b-9e28-9f22c7b44feb" xlink:to="loc_us-gaap_Goodwill_8b086163-f008-4d9f-9065-52433ab280d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_45343338-866f-4838-b6b3-d8ddf7b91550" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_594c66e7-5758-495b-9e28-9f22c7b44feb" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_45343338-866f-4838-b6b3-d8ddf7b91550" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_675238d0-d7e3-4615-842f-f01b22af3746" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_594c66e7-5758-495b-9e28-9f22c7b44feb" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_675238d0-d7e3-4615-842f-f01b22af3746" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_ecf33fbb-cbec-46b0-8c6b-3ba3a0a66b16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_594c66e7-5758-495b-9e28-9f22c7b44feb" xlink:to="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_ecf33fbb-cbec-46b0-8c6b-3ba3a0a66b16" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_3e55ea48-7ba7-46e0-86c7-e6ff0f4e88f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_594c66e7-5758-495b-9e28-9f22c7b44feb" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_3e55ea48-7ba7-46e0-86c7-e6ff0f4e88f8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_c8decbc0-e516-4123-8507-f5989f1de806" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesComponentsofIntangibleAssetsSubjecttoAmortizationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#GoodwillandOtherIntangiblesComponentsofIntangibleAssetsSubjecttoAmortizationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesComponentsofIntangibleAssetsSubjecttoAmortizationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5e086573-d963-4b4c-9454-2bafae44d16a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_481548af-5872-4ef3-9461-bb301ea7da72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5e086573-d963-4b4c-9454-2bafae44d16a" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_481548af-5872-4ef3-9461-bb301ea7da72" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6389ee84-dbdc-4372-b6f5-f156a22f19b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_481548af-5872-4ef3-9461-bb301ea7da72" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6389ee84-dbdc-4372-b6f5-f156a22f19b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6389ee84-dbdc-4372-b6f5-f156a22f19b1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6389ee84-dbdc-4372-b6f5-f156a22f19b1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_6389ee84-dbdc-4372-b6f5-f156a22f19b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6389ee84-dbdc-4372-b6f5-f156a22f19b1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmissionAllowancesMember_422c4eae-ff4a-4226-b572-00e075aabcc4" xlink:href="nrg-20231231.xsd#nrg_EmissionAllowancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:to="loc_nrg_EmissionAllowancesMember_422c4eae-ff4a-4226-b572-00e075aabcc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CustomerAndSupplyContractsMember_6194427e-9c7b-4c9d-a049-50088ad3886f" xlink:href="nrg-20231231.xsd#nrg_CustomerAndSupplyContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:to="loc_nrg_CustomerAndSupplyContractsMember_6194427e-9c7b-4c9d-a049-50088ad3886f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_a67112ee-5a1c-4646-b0af-61d16ac9b733" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:to="loc_us-gaap_CustomerRelationshipsMember_a67112ee-5a1c-4646-b0af-61d16ac9b733" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MarketingPartnershipsMember_13f37a46-eece-469e-ac9b-0210ba450666" xlink:href="nrg-20231231.xsd#nrg_MarketingPartnershipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:to="loc_nrg_MarketingPartnershipsMember_13f37a46-eece-469e-ac9b-0210ba450666" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_55cd6335-63f7-4fa1-9b45-5c6dbfdc2bc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_55cd6335-63f7-4fa1-9b45-5c6dbfdc2bc0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_860bb4bf-b563-495b-8d5b-1b78b38f4e0d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:to="loc_us-gaap_TradeNamesMember_860bb4bf-b563-495b-8d5b-1b78b38f4e0d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OtherFiniteLivedIntangibleAssetsMember_71cfc4c7-39fe-41bb-801f-ae53a47b8a31" xlink:href="nrg-20231231.xsd#nrg_OtherFiniteLivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_391f984e-f3e5-4210-b865-dfb1093e42aa" xlink:to="loc_nrg_OtherFiniteLivedIntangibleAssetsMember_71cfc4c7-39fe-41bb-801f-ae53a47b8a31" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b21f0c80-15d6-4cbf-86af-01ab04c5d350" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_481548af-5872-4ef3-9461-bb301ea7da72" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b21f0c80-15d6-4cbf-86af-01ab04c5d350" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b21f0c80-15d6-4cbf-86af-01ab04c5d350_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b21f0c80-15d6-4cbf-86af-01ab04c5d350" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b21f0c80-15d6-4cbf-86af-01ab04c5d350_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_6c8221a2-ec8d-40e6-b1a5-9c27f818b58a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b21f0c80-15d6-4cbf-86af-01ab04c5d350" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_6c8221a2-ec8d-40e6-b1a5-9c27f818b58a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RenewableEnergyCertificatesMember_157eb371-edf9-4394-a3b7-cf6fb909eaff" xlink:href="nrg-20231231.xsd#nrg_RenewableEnergyCertificatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_6c8221a2-ec8d-40e6-b1a5-9c27f818b58a" xlink:to="loc_nrg_RenewableEnergyCertificatesMember_157eb371-edf9-4394-a3b7-cf6fb909eaff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_b916c004-806b-4872-86b9-8a9d32db2632" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_481548af-5872-4ef3-9461-bb301ea7da72" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_b916c004-806b-4872-86b9-8a9d32db2632" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b916c004-806b-4872-86b9-8a9d32db2632_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_b916c004-806b-4872-86b9-8a9d32db2632" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b916c004-806b-4872-86b9-8a9d32db2632_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_851da979-30ed-4fda-b7ea-b388c95dc307" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_b916c004-806b-4872-86b9-8a9d32db2632" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_851da979-30ed-4fda-b7ea-b388c95dc307" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintMember_024206a8-f98b-4e69-963c-e3ec7af51fbb" xlink:href="nrg-20231231.xsd#nrg_VivintMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_851da979-30ed-4fda-b7ea-b388c95dc307" xlink:to="loc_nrg_VivintMember_024206a8-f98b-4e69-963c-e3ec7af51fbb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_255af4fa-78f2-4ab1-8872-df26617ab41a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_481548af-5872-4ef3-9461-bb301ea7da72" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_255af4fa-78f2-4ab1-8872-df26617ab41a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_255af4fa-78f2-4ab1-8872-df26617ab41a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_255af4fa-78f2-4ab1-8872-df26617ab41a" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_255af4fa-78f2-4ab1-8872-df26617ab41a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a8ed100e-4951-4a24-8f64-0db6e712cfc2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_255af4fa-78f2-4ab1-8872-df26617ab41a" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a8ed100e-4951-4a24-8f64-0db6e712cfc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_de918074-e593-4f47-bf31-c8c12f88cde9" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a8ed100e-4951-4a24-8f64-0db6e712cfc2" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_de918074-e593-4f47-bf31-c8c12f88cde9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_d823c6b6-2c42-4c24-8b50-a3aa88b742fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_481548af-5872-4ef3-9461-bb301ea7da72" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_d823c6b6-2c42-4c24-8b50-a3aa88b742fc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_d823c6b6-2c42-4c24-8b50-a3aa88b742fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_d823c6b6-2c42-4c24-8b50-a3aa88b742fc" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_d823c6b6-2c42-4c24-8b50-a3aa88b742fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_ef3ae816-6e45-4b1d-be67-6bfc90bb373f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_d823c6b6-2c42-4c24-8b50-a3aa88b742fc" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_ef3ae816-6e45-4b1d-be67-6bfc90bb373f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_101f5c5e-0dc2-4165-8c91-39e838056b49" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_ef3ae816-6e45-4b1d-be67-6bfc90bb373f" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_101f5c5e-0dc2-4165-8c91-39e838056b49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5e086573-d963-4b4c-9454-2bafae44d16a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_b464ee7d-255c-4cbb-8310-fc5bfd877407" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_b464ee7d-255c-4cbb-8310-fc5bfd877407" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FiniteLivedIntangibleAssetsPurchases_a9d6bbe4-ffb7-4dc8-9d65-da5c48b3abef" xlink:href="nrg-20231231.xsd#nrg_FiniteLivedIntangibleAssetsPurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:to="loc_nrg_FiniteLivedIntangibleAssetsPurchases_a9d6bbe4-ffb7-4dc8-9d65-da5c48b3abef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_a4ff971f-310b-4708-bde9-7d83472a6d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_a4ff971f-310b-4708-bde9-7d83472a6d1e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FiniteLivedIntangibleAssetsUsageAndRetirements_4893cd4c-1755-4a46-a231-19b8dae557e4" xlink:href="nrg-20231231.xsd#nrg_FiniteLivedIntangibleAssetsUsageAndRetirements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:to="loc_nrg_FiniteLivedIntangibleAssetsUsageAndRetirements_4893cd4c-1755-4a46-a231-19b8dae557e4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FiniteLivedIntangibleAssetsWriteOffOfFullyAmortizedIntangibleAssets_118c6562-b655-4b15-a3c8-3116f7970199" xlink:href="nrg-20231231.xsd#nrg_FiniteLivedIntangibleAssetsWriteOffOfFullyAmortizedIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:to="loc_nrg_FiniteLivedIntangibleAssetsWriteOffOfFullyAmortizedIntangibleAssets_118c6562-b655-4b15-a3c8-3116f7970199" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FiniteLivedIntangibleAssetsDisposalOfIntangibleAssetsOfEquityMethodInvestment_ec1d8c7d-1363-4845-8a09-f6fbcf84eba5" xlink:href="nrg-20231231.xsd#nrg_FiniteLivedIntangibleAssetsDisposalOfIntangibleAssetsOfEquityMethodInvestment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:to="loc_nrg_FiniteLivedIntangibleAssetsDisposalOfIntangibleAssetsOfEquityMethodInvestment_ec1d8c7d-1363-4845-8a09-f6fbcf84eba5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FiniteLivedIntangibleAssetsOtherChanges_a4d7ba2d-9fcd-449b-aef5-76b3c8ca6f18" xlink:href="nrg-20231231.xsd#nrg_FiniteLivedIntangibleAssetsOtherChanges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsRollForward_e6825a24-eeb4-4da6-a8a9-fcead43d5c0b" xlink:to="loc_nrg_FiniteLivedIntangibleAssetsOtherChanges_a4d7ba2d-9fcd-449b-aef5-76b3c8ca6f18" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_6cb4c353-c45f-4831-956f-f7f74a31acd7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_47fd81b3-1455-4a1e-bd7e-0ec02edf005b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5e086573-d963-4b4c-9454-2bafae44d16a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_47fd81b3-1455-4a1e-bd7e-0ec02edf005b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_bc92642c-b1c1-4302-b361-dcc7fdeaaaa4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5e086573-d963-4b4c-9454-2bafae44d16a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_bc92642c-b1c1-4302-b361-dcc7fdeaaaa4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_64c63cea-16be-41cd-aaa1-1a11fc9d74cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5e086573-d963-4b4c-9454-2bafae44d16a" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_64c63cea-16be-41cd-aaa1-1a11fc9d74cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_cd5cf297-3e75-4dc3-a5c0-0c6f09773bb5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5e086573-d963-4b4c-9454-2bafae44d16a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_cd5cf297-3e75-4dc3-a5c0-0c6f09773bb5" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesScheduleofAmortizationandRetirementofIntangibleAssetsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#GoodwillandOtherIntangiblesScheduleofAmortizationandRetirementofIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesScheduleofAmortizationandRetirementofIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_771c446a-93f3-49fd-a33a-d3601f1c08c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_de783351-8412-4b87-8b4d-1098bf54dc7a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_771c446a-93f3-49fd-a33a-d3601f1c08c3" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_de783351-8412-4b87-8b4d-1098bf54dc7a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_aa9413e4-fb86-49df-ba15-489ddd7fb82b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_de783351-8412-4b87-8b4d-1098bf54dc7a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_aa9413e4-fb86-49df-ba15-489ddd7fb82b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_aa9413e4-fb86-49df-ba15-489ddd7fb82b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_aa9413e4-fb86-49df-ba15-489ddd7fb82b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_aa9413e4-fb86-49df-ba15-489ddd7fb82b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_aa9413e4-fb86-49df-ba15-489ddd7fb82b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmissionAllowancesMember_e849cb4f-bcff-43b3-bb5d-298d906553b7" xlink:href="nrg-20231231.xsd#nrg_EmissionAllowancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:to="loc_nrg_EmissionAllowancesMember_e849cb4f-bcff-43b3-bb5d-298d906553b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CustomerAndSupplyContractsMember_ae787f8f-04c2-4423-bd62-c6cad5aed8b6" xlink:href="nrg-20231231.xsd#nrg_CustomerAndSupplyContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:to="loc_nrg_CustomerAndSupplyContractsMember_ae787f8f-04c2-4423-bd62-c6cad5aed8b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_08faedb6-c6e3-4692-83b4-b63485441dc3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:to="loc_us-gaap_CustomerRelationshipsMember_08faedb6-c6e3-4692-83b4-b63485441dc3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MarketingPartnershipsMember_ea1bd50e-d0e6-4831-8b2b-a55d4b332c2e" xlink:href="nrg-20231231.xsd#nrg_MarketingPartnershipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:to="loc_nrg_MarketingPartnershipsMember_ea1bd50e-d0e6-4831-8b2b-a55d4b332c2e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_156ed0c4-3a06-4fe4-8a6a-0d3d7fccec9a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_156ed0c4-3a06-4fe4-8a6a-0d3d7fccec9a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_9db4c49d-add8-40a2-8799-39ed0406c46f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:to="loc_us-gaap_TradeNamesMember_9db4c49d-add8-40a2-8799-39ed0406c46f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OtherFiniteLivedIntangibleAssetsMember_fe803e4e-85f7-408b-9b91-99a48999cdff" xlink:href="nrg-20231231.xsd#nrg_OtherFiniteLivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_005c6697-62ed-43bd-97c9-8ff43058819f" xlink:to="loc_nrg_OtherFiniteLivedIntangibleAssetsMember_fe803e4e-85f7-408b-9b91-99a48999cdff" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_073e1808-f36b-494a-944d-1aae3801f667" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_de783351-8412-4b87-8b4d-1098bf54dc7a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_073e1808-f36b-494a-944d-1aae3801f667" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_073e1808-f36b-494a-944d-1aae3801f667_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_073e1808-f36b-494a-944d-1aae3801f667" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_073e1808-f36b-494a-944d-1aae3801f667_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_0de582eb-abad-46f9-b6a4-d659dac0927d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_073e1808-f36b-494a-944d-1aae3801f667" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_0de582eb-abad-46f9-b6a4-d659dac0927d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RenewableEnergyCertificatesMember_00785784-6a1d-4612-bb25-4eaf257b5a33" xlink:href="nrg-20231231.xsd#nrg_RenewableEnergyCertificatesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_0de582eb-abad-46f9-b6a4-d659dac0927d" xlink:to="loc_nrg_RenewableEnergyCertificatesMember_00785784-6a1d-4612-bb25-4eaf257b5a33" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_63d9317c-5efa-4824-84a8-95cd450f9466" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_771c446a-93f3-49fd-a33a-d3601f1c08c3" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_63d9317c-5efa-4824-84a8-95cd450f9466" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAmortizationAndAccretionNet_4836ccc4-45ae-4f4c-bc58-32130d4cdabe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationAmortizationAndAccretionNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_771c446a-93f3-49fd-a33a-d3601f1c08c3" xlink:to="loc_us-gaap_DepreciationAmortizationAndAccretionNet_4836ccc4-45ae-4f4c-bc58-32130d4cdabe" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesScheduleofEstimatedAmortizationofIntangibleAssetfortheNextFiveYearsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#GoodwillandOtherIntangiblesScheduleofEstimatedAmortizationofIntangibleAssetfortheNextFiveYearsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesScheduleofEstimatedAmortizationofIntangibleAssetfortheNextFiveYearsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_d4ff1565-37d5-49bb-8f04-ab9f5562d87b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4c679f6c-e870-4bbe-a291-7ec2bd372b2c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_d4ff1565-37d5-49bb-8f04-ab9f5562d87b" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4c679f6c-e870-4bbe-a291-7ec2bd372b2c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e07444b6-8bad-459f-89c1-2554987d306d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_4c679f6c-e870-4bbe-a291-7ec2bd372b2c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e07444b6-8bad-459f-89c1-2554987d306d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e07444b6-8bad-459f-89c1-2554987d306d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e07444b6-8bad-459f-89c1-2554987d306d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e07444b6-8bad-459f-89c1-2554987d306d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e07444b6-8bad-459f-89c1-2554987d306d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmissionAllowancesMember_d7a55ade-2bca-47f8-b621-dd44b4f8ba6e" xlink:href="nrg-20231231.xsd#nrg_EmissionAllowancesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:to="loc_nrg_EmissionAllowancesMember_d7a55ade-2bca-47f8-b621-dd44b4f8ba6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CustomerAndSupplyContractsMember_b27001e0-608f-404f-9907-db67d4163ff0" xlink:href="nrg-20231231.xsd#nrg_CustomerAndSupplyContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:to="loc_nrg_CustomerAndSupplyContractsMember_b27001e0-608f-404f-9907-db67d4163ff0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_40594cd9-4e3f-48c2-84ec-240bff34616e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:to="loc_us-gaap_CustomerRelationshipsMember_40594cd9-4e3f-48c2-84ec-240bff34616e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MarketingPartnershipsMember_590ce2e6-7b4e-4d40-9b20-5508eebac003" xlink:href="nrg-20231231.xsd#nrg_MarketingPartnershipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:to="loc_nrg_MarketingPartnershipsMember_590ce2e6-7b4e-4d40-9b20-5508eebac003" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_c7f6c974-26de-46df-8139-997fdf5c48b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_c7f6c974-26de-46df-8139-997fdf5c48b6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_3bbf6c93-f26b-4cc5-90e7-2d6c2ba98c8e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:to="loc_us-gaap_TradeNamesMember_3bbf6c93-f26b-4cc5-90e7-2d6c2ba98c8e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OtherFiniteLivedIntangibleAssetsMember_2ecf85b4-4368-427b-a160-5ef15dc9c4ff" xlink:href="nrg-20231231.xsd#nrg_OtherFiniteLivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_927a135b-07ea-40ec-ab11-6d19796ad86b" xlink:to="loc_nrg_OtherFiniteLivedIntangibleAssetsMember_2ecf85b4-4368-427b-a160-5ef15dc9c4ff" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_110c92de-a0bf-435a-9a7d-b4c6463b911e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_d4ff1565-37d5-49bb-8f04-ab9f5562d87b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_110c92de-a0bf-435a-9a7d-b4c6463b911e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_553351ee-6aad-4a96-9d66-13069707e4b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_110c92de-a0bf-435a-9a7d-b4c6463b911e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_553351ee-6aad-4a96-9d66-13069707e4b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_33124b63-654c-43bd-9a00-539b1662da09" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_110c92de-a0bf-435a-9a7d-b4c6463b911e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_33124b63-654c-43bd-9a00-539b1662da09" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_20fbac65-b423-441a-bd5d-566d017b768e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_110c92de-a0bf-435a-9a7d-b4c6463b911e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_20fbac65-b423-441a-bd5d-566d017b768e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_d0dd5a72-8584-4211-aae5-672b28083576" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_110c92de-a0bf-435a-9a7d-b4c6463b911e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_d0dd5a72-8584-4211-aae5-672b28083576" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_ba1a2e91-affc-4dfe-a615-05c661e06070" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_110c92de-a0bf-435a-9a7d-b4c6463b911e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_ba1a2e91-affc-4dfe-a615-05c661e06070" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#GoodwillandOtherIntangiblesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/GoodwillandOtherIntangiblesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_a87898cf-7ad2-449c-b92f-0d06370775a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e47cec07-b8b9-49f4-99eb-7b16e0253e14" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_a87898cf-7ad2-449c-b92f-0d06370775a2" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e47cec07-b8b9-49f4-99eb-7b16e0253e14" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_9f8c685d-68c8-4ca3-ac44-d221564f9881" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e47cec07-b8b9-49f4-99eb-7b16e0253e14" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_9f8c685d-68c8-4ca3-ac44-d221564f9881" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_9f8c685d-68c8-4ca3-ac44-d221564f9881_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_9f8c685d-68c8-4ca3-ac44-d221564f9881" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_9f8c685d-68c8-4ca3-ac44-d221564f9881_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_93d23c6b-92de-4644-ae6b-2ca0b9f5d922" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_9f8c685d-68c8-4ca3-ac44-d221564f9881" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_93d23c6b-92de-4644-ae6b-2ca0b9f5d922" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember_f2450958-751f-43a0-b00c-30fa61265faa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_93d23c6b-92de-4644-ae6b-2ca0b9f5d922" xlink:to="loc_us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember_f2450958-751f-43a0-b00c-30fa61265faa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OtherAssetsNoncurrentEmissionAllowances_ada2be08-ee16-420c-a74a-a719727d020f" xlink:href="nrg-20231231.xsd#nrg_OtherAssetsNoncurrentEmissionAllowances"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_a87898cf-7ad2-449c-b92f-0d06370775a2" xlink:to="loc_nrg_OtherAssetsNoncurrentEmissionAllowances_ada2be08-ee16-420c-a74a-a719727d020f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesScheduleofLongtermDebtandFinanceLeasesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesScheduleofLongtermDebtandFinanceLeasesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesScheduleofLongtermDebtandFinanceLeasesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_94d9d9a6-178c-4a02-851f-e497afed1023" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DebtInstrumentTable_94d9d9a6-178c-4a02-851f-e497afed1023" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_92d3cd63-2da1-4524-9fb8-1272f31e041a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_94d9d9a6-178c-4a02-851f-e497afed1023" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_92d3cd63-2da1-4524-9fb8-1272f31e041a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_92d3cd63-2da1-4524-9fb8-1272f31e041a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_92d3cd63-2da1-4524-9fb8-1272f31e041a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_92d3cd63-2da1-4524-9fb8-1272f31e041a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_84d25b5f-4b97-4c1e-b4a6-0abbd8d7785c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_92d3cd63-2da1-4524-9fb8-1272f31e041a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_84d25b5f-4b97-4c1e-b4a6-0abbd8d7785c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RecourseDebtMember_02f228cc-6182-423d-b6c0-9d98512c3cd3" xlink:href="nrg-20231231.xsd#nrg_RecourseDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_84d25b5f-4b97-4c1e-b4a6-0abbd8d7785c" xlink:to="loc_nrg_RecourseDebtMember_02f228cc-6182-423d-b6c0-9d98512c3cd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NonRecourseDebtMember_ed673680-313b-4125-abce-4f4cd2e48784" xlink:href="nrg-20231231.xsd#nrg_NonRecourseDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_84d25b5f-4b97-4c1e-b4a6-0abbd8d7785c" xlink:to="loc_nrg_NonRecourseDebtMember_ed673680-313b-4125-abce-4f4cd2e48784" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_f7f4f04e-0707-4658-86e6-03598373acf3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_94d9d9a6-178c-4a02-851f-e497afed1023" xlink:to="loc_us-gaap_DebtInstrumentAxis_f7f4f04e-0707-4658-86e6-03598373acf3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_f7f4f04e-0707-4658-86e6-03598373acf3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_f7f4f04e-0707-4658-86e6-03598373acf3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_f7f4f04e-0707-4658-86e6-03598373acf3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_f7f4f04e-0707-4658-86e6-03598373acf3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2027Member_3397d7f5-8461-40bf-b630-0d688d329b76" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_SeniorNotesdue2027Member_3397d7f5-8461-40bf-b630-0d688d329b76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2028Member_b292874f-ff3f-474b-80d8-ecc927e7e5e0" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_SeniorNotesdue2028Member_b292874f-ff3f-474b-80d8-ecc927e7e5e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A5250SeniorNotesDue2029Member_e5cfd31e-6389-41d8-9708-5774124ac50b" xlink:href="nrg-20231231.xsd#nrg_A5250SeniorNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_A5250SeniorNotesDue2029Member_e5cfd31e-6389-41d8-9708-5774124ac50b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_72a8b9b0-ad2d-466b-b460-0facf89b944d" xlink:href="nrg-20231231.xsd#nrg_A3375SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_72a8b9b0-ad2d-466b-b460-0facf89b944d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3625SeniorUnsecuredNotesDue2031Member_116029ba-5c76-4483-b7e6-9d15aa052d56" xlink:href="nrg-20231231.xsd#nrg_A3625SeniorUnsecuredNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_A3625SeniorUnsecuredNotesDue2031Member_116029ba-5c76-4483-b7e6-9d15aa052d56" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3875SeniorNotesDue2032Member_9b5452b0-f858-4a51-b9de-13eb6ece8676" xlink:href="nrg-20231231.xsd#nrg_A3875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_A3875SeniorNotesDue2032Member_9b5452b0-f858-4a51-b9de-13eb6ece8676" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConvertibleSeniorNotesDue2048Member_11c3ad45-b0c5-4e99-97b3-c13284099cee" xlink:href="nrg-20231231.xsd#nrg_ConvertibleSeniorNotesDue2048Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_ConvertibleSeniorNotesDue2048Member_11c3ad45-b0c5-4e99-97b3-c13284099cee" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorSecuredFirstLienNotesDue2024Member_681deb51-7de9-47de-a122-ff785ce65ab3" xlink:href="nrg-20231231.xsd#nrg_SeniorSecuredFirstLienNotesDue2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_SeniorSecuredFirstLienNotesDue2024Member_681deb51-7de9-47de-a122-ff785ce65ab3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A2000SeniorSecuredNotesDue2025Member_e1d8875f-194a-4fba-8bce-a860be7ef4c5" xlink:href="nrg-20231231.xsd#nrg_A2000SeniorSecuredNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_A2000SeniorSecuredNotesDue2025Member_e1d8875f-194a-4fba-8bce-a860be7ef4c5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A2450SeniorSecuredNotesDue2027Member_6ef1ac3b-46d4-43ed-aeb4-90327179c976" xlink:href="nrg-20231231.xsd#nrg_A2450SeniorSecuredNotesDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_A2450SeniorSecuredNotesDue2027Member_6ef1ac3b-46d4-43ed-aeb4-90327179c976" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorSecuredFirstLienNotesDue2029Member_da1d642c-7177-435a-9528-716d03a82b89" xlink:href="nrg-20231231.xsd#nrg_SeniorSecuredFirstLienNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_SeniorSecuredFirstLienNotesDue2029Member_da1d642c-7177-435a-9528-716d03a82b89" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A7000SeniorSecuredFirstLienNotesDue2033Member_56125037-3822-4256-82f3-702cff4ee26f" xlink:href="nrg-20231231.xsd#nrg_A7000SeniorSecuredFirstLienNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_A7000SeniorSecuredFirstLienNotesDue2033Member_56125037-3822-4256-82f3-702cff4ee26f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TaxexemptBondsMember_6a34b160-8c1a-45e1-b594-04cc19859cec" xlink:href="nrg-20231231.xsd#nrg_TaxexemptBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_TaxexemptBondsMember_6a34b160-8c1a-45e1-b594-04cc19859cec" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_Vivint5750SeniorSecuredNotesDue2029Member_467635c4-9de5-4166-852a-7c1a37f1f535" xlink:href="nrg-20231231.xsd#nrg_Vivint5750SeniorSecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_Vivint5750SeniorSecuredNotesDue2029Member_467635c4-9de5-4166-852a-7c1a37f1f535" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_Vivint6750SeniorSecuredNotesDue2027Member_a8f8e0ee-ae18-41a6-ba06-2b6b0f720c31" xlink:href="nrg-20231231.xsd#nrg_Vivint6750SeniorSecuredNotesDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_Vivint6750SeniorSecuredNotesDue2027Member_a8f8e0ee-ae18-41a6-ba06-2b6b0f720c31" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSeniorSecuredNotesDue2028Member_cd856f38-f701-4da2-b22a-d1ef99d7d1a0" xlink:href="nrg-20231231.xsd#nrg_VivintSeniorSecuredNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_VivintSeniorSecuredNotesDue2028Member_cd856f38-f701-4da2-b22a-d1ef99d7d1a0" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorSecuredFirstLienNotesDue202420252027And2029Member_3bbd64e3-9804-48f2-98fb-0034e7ff914f" xlink:href="nrg-20231231.xsd#nrg_SeniorSecuredFirstLienNotesDue202420252027And2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_e386d210-7632-42ed-ae19-4c5ab4468be6" xlink:to="loc_nrg_SeniorSecuredFirstLienNotesDue202420252027And2029Member_3bbd64e3-9804-48f2-98fb-0034e7ff914f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_c1abbcd4-3fa1-4aeb-a0b5-b03f0d215cd3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_94d9d9a6-178c-4a02-851f-e497afed1023" xlink:to="loc_srt_RangeAxis_c1abbcd4-3fa1-4aeb-a0b5-b03f0d215cd3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c1abbcd4-3fa1-4aeb-a0b5-b03f0d215cd3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_c1abbcd4-3fa1-4aeb-a0b5-b03f0d215cd3" xlink:to="loc_srt_RangeMember_c1abbcd4-3fa1-4aeb-a0b5-b03f0d215cd3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_67d38609-3944-43b5-8334-89c6ffb34763" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_c1abbcd4-3fa1-4aeb-a0b5-b03f0d215cd3" xlink:to="loc_srt_RangeMember_67d38609-3944-43b5-8334-89c6ffb34763" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_91242a2e-9c19-4caf-9290-8a062d70d813" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_67d38609-3944-43b5-8334-89c6ffb34763" xlink:to="loc_srt_MinimumMember_91242a2e-9c19-4caf-9290-8a062d70d813" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_dd47738a-3368-4ea5-8f7e-253248bfdaeb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_67d38609-3944-43b5-8334-89c6ffb34763" xlink:to="loc_srt_MaximumMember_dd47738a-3368-4ea5-8f7e-253248bfdaeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_e14ad660-82b4-4ddd-a66c-d56ebdb9e7ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_94d9d9a6-178c-4a02-851f-e497afed1023" xlink:to="loc_us-gaap_VariableRateAxis_e14ad660-82b4-4ddd-a66c-d56ebdb9e7ce" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_e14ad660-82b4-4ddd-a66c-d56ebdb9e7ce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_e14ad660-82b4-4ddd-a66c-d56ebdb9e7ce" xlink:to="loc_us-gaap_VariableRateDomain_e14ad660-82b4-4ddd-a66c-d56ebdb9e7ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_9f4f810b-84ed-434c-88fb-7dceefb538c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_e14ad660-82b4-4ddd-a66c-d56ebdb9e7ce" xlink:to="loc_us-gaap_VariableRateDomain_9f4f810b-84ed-434c-88fb-7dceefb538c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_f78e1615-9959-4a0e-b009-b44c71a7df22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_9f4f810b-84ed-434c-88fb-7dceefb538c0" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_f78e1615-9959-4a0e-b009-b44c71a7df22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_9953c47c-aac3-4ba2-864c-8d2d9d9fb540" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_94d9d9a6-178c-4a02-851f-e497afed1023" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_9953c47c-aac3-4ba2-864c-8d2d9d9fb540" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_9953c47c-aac3-4ba2-864c-8d2d9d9fb540_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9953c47c-aac3-4ba2-864c-8d2d9d9fb540" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_9953c47c-aac3-4ba2-864c-8d2d9d9fb540_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_13a3c72f-4b85-4245-a57f-571e0fc890f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9953c47c-aac3-4ba2-864c-8d2d9d9fb540" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_13a3c72f-4b85-4245-a57f-571e0fc890f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_10d0af83-d8b1-4426-b021-07e8c41edac8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_13a3c72f-4b85-4245-a57f-571e0fc890f6" xlink:to="loc_us-gaap_SubsequentEventMember_10d0af83-d8b1-4426-b021-07e8c41edac8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_d605c7dc-1524-4a4b-a397-e3ba31922400" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_LongTermDebt_d605c7dc-1524-4a4b-a397-e3ba31922400" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_bfd190ce-41cf-4cdc-8574-2f2de71cb7de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_FinanceLeaseLiability_bfd190ce-41cf-4cdc-8574-2f2de71cb7de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityStatementOfFinancialPositionExtensibleList_fde2749d-bec0-4d42-a891-c6492b5730da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityStatementOfFinancialPositionExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_FinanceLeaseLiabilityStatementOfFinancialPositionExtensibleList_fde2749d-bec0-4d42-a891-c6492b5730da" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_afee8862-7439-4511-b941-3b86ce8562b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_afee8862-7439-4511-b941-3b86ce8562b1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_bbbd804b-17be-438f-bda7-f7faa2fb2cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_bbbd804b-17be-438f-bda7-f7faa2fb2cc7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_2e09f6ea-968d-4b79-9943-f7f1f636523e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_2e09f6ea-968d-4b79-9943-f7f1f636523e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_373567e5-d70b-4d87-9c12-092a4ac825d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_373567e5-d70b-4d87-9c12-092a4ac825d1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_c61f15d3-aae9-446a-b1ae-15c90f7f8abd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_c61f15d3-aae9-446a-b1ae-15c90f7f8abd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_dda1f8c0-b8ae-47a0-b22c-a86fa72ec113" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_dda1f8c0-b8ae-47a0-b22c-a86fa72ec113" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_83ed1c7e-4bca-4cd8-9d14-337977ab9ba4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_83ed1c7e-4bca-4cd8-9d14-337977ab9ba4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_10185ce5-72b7-47e6-b719-8677d118fcb7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_10185ce5-72b7-47e6-b719-8677d118fcb7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountAbstract_4e141fbe-9e55-40fc-817d-4bc7999ada08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscountAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_fccdfa61-2be8-44ac-9cd3-3e705f482c3e" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountAbstract_4e141fbe-9e55-40fc-817d-4bc7999ada08" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet_1c7fda14-acb8-4aa7-b849-d3c640165df0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesRevolvingCreditFacilityDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesRevolvingCreditFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesRevolvingCreditFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_8f1f19e7-a1d6-46f2-99ba-19f0041bbabc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_8f1f19e7-a1d6-46f2-99ba-19f0041bbabc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_7e6a1a8a-cba3-4ba0-92af-a4b7d2683c8f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_8f1f19e7-a1d6-46f2-99ba-19f0041bbabc" xlink:to="loc_us-gaap_DebtInstrumentAxis_7e6a1a8a-cba3-4ba0-92af-a4b7d2683c8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7e6a1a8a-cba3-4ba0-92af-a4b7d2683c8f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7e6a1a8a-cba3-4ba0-92af-a4b7d2683c8f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7e6a1a8a-cba3-4ba0-92af-a4b7d2683c8f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_64e20256-fe27-4fc0-ae2c-a213538d5861" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7e6a1a8a-cba3-4ba0-92af-a4b7d2683c8f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_64e20256-fe27-4fc0-ae2c-a213538d5861" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RevolvingCreditFacilityAgreementMember_66e18a9a-f0c5-47af-91e6-89cfe27e7381" xlink:href="nrg-20231231.xsd#nrg_RevolvingCreditFacilityAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_64e20256-fe27-4fc0-ae2c-a213538d5861" xlink:to="loc_nrg_RevolvingCreditFacilityAgreementMember_66e18a9a-f0c5-47af-91e6-89cfe27e7381" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_4f5c546f-570c-427c-959d-d98cd3c5bbd6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_8f1f19e7-a1d6-46f2-99ba-19f0041bbabc" xlink:to="loc_us-gaap_CreditFacilityAxis_4f5c546f-570c-427c-959d-d98cd3c5bbd6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_4f5c546f-570c-427c-959d-d98cd3c5bbd6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_4f5c546f-570c-427c-959d-d98cd3c5bbd6" xlink:to="loc_us-gaap_CreditFacilityDomain_4f5c546f-570c-427c-959d-d98cd3c5bbd6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6eeb18a7-d7b4-478b-b46b-da92c5db7990" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_4f5c546f-570c-427c-959d-d98cd3c5bbd6" xlink:to="loc_us-gaap_CreditFacilityDomain_6eeb18a7-d7b4-478b-b46b-da92c5db7990" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_08459749-22a9-4bdc-87c7-08d03c939264" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6eeb18a7-d7b4-478b-b46b-da92c5db7990" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_08459749-22a9-4bdc-87c7-08d03c939264" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_5251eb95-f528-40d7-9920-6c35f88dc675" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6eeb18a7-d7b4-478b-b46b-da92c5db7990" xlink:to="loc_us-gaap_LetterOfCreditMember_5251eb95-f528-40d7-9920-6c35f88dc675" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity_6a32d5b2-8181-49bf-9fb2-c9bb89328c64" xlink:href="nrg-20231231.xsd#nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:to="loc_nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity_6a32d5b2-8181-49bf-9fb2-c9bb89328c64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_af51f35d-17e4-4202-881b-163db8582fba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_af51f35d-17e4-4202-881b-163db8582fba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DebtCollateralExclusionEquityInterestsExceedsPercentageOfTotalOutstandingVotingEquityInterestsOfCertainForeignSubsidiaries_3cd80d93-9bba-4c90-a2f1-88ad954a9bf3" xlink:href="nrg-20231231.xsd#nrg_DebtCollateralExclusionEquityInterestsExceedsPercentageOfTotalOutstandingVotingEquityInterestsOfCertainForeignSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:to="loc_nrg_DebtCollateralExclusionEquityInterestsExceedsPercentageOfTotalOutstandingVotingEquityInterestsOfCertainForeignSubsidiaries_3cd80d93-9bba-4c90-a2f1-88ad954a9bf3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DebtInstrumentCollateralExcludedSubsidiariesAndOtherAssetsWithAggregateFairValueMaximum_969c03f3-9d26-42e8-a8a3-ae83b617e423" xlink:href="nrg-20231231.xsd#nrg_DebtInstrumentCollateralExcludedSubsidiariesAndOtherAssetsWithAggregateFairValueMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:to="loc_nrg_DebtInstrumentCollateralExcludedSubsidiariesAndOtherAssetsWithAggregateFairValueMaximum_969c03f3-9d26-42e8-a8a3-ae83b617e423" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_2510ec46-483b-4d91-b158-f669717aada0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:to="loc_us-gaap_LineOfCredit_2510ec46-483b-4d91-b158-f669717aada0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_c6b668d6-017f-466c-a746-db6c2d6700a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_ce648dd1-5188-49c3-8039-33b69fac305e" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_c6b668d6-017f-466c-a746-db6c2d6700a4" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesIssuanceandRedemptionsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesSeniorNotesIssuanceandRedemptionsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesIssuanceandRedemptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_fbe6f7b3-0b73-4414-8866-e103ed69208f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_DebtInstrumentTable_fbe6f7b3-0b73-4414-8866-e103ed69208f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_c72a0e36-3b4d-4c8c-a5fa-d8201593033d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_fbe6f7b3-0b73-4414-8866-e103ed69208f" xlink:to="loc_us-gaap_DebtInstrumentAxis_c72a0e36-3b4d-4c8c-a5fa-d8201593033d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c72a0e36-3b4d-4c8c-a5fa-d8201593033d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_c72a0e36-3b4d-4c8c-a5fa-d8201593033d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c72a0e36-3b4d-4c8c-a5fa-d8201593033d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_1b28db20-f337-4439-a647-72797b5c6d99" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_c72a0e36-3b4d-4c8c-a5fa-d8201593033d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_1b28db20-f337-4439-a647-72797b5c6d99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A7000SeniorSecuredFirstLienNotesDue2033Member_bcc8210f-e563-4936-8cd3-6c1ff5274796" xlink:href="nrg-20231231.xsd#nrg_A7000SeniorSecuredFirstLienNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1b28db20-f337-4439-a647-72797b5c6d99" xlink:to="loc_nrg_A7000SeniorSecuredFirstLienNotesDue2033Member_bcc8210f-e563-4936-8cd3-6c1ff5274796" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3875SeniorNotesDue2032Member_7e18ef85-5ace-49b3-aae8-fcbb2b8afe51" xlink:href="nrg-20231231.xsd#nrg_A3875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1b28db20-f337-4439-a647-72797b5c6d99" xlink:to="loc_nrg_A3875SeniorNotesDue2032Member_7e18ef85-5ace-49b3-aae8-fcbb2b8afe51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_ba17e7a1-eb54-46c8-96d0-33c067e862f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1b28db20-f337-4439-a647-72797b5c6d99" xlink:to="loc_us-gaap_SeniorNotesMember_ba17e7a1-eb54-46c8-96d0-33c067e862f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_adba6f7f-5472-4061-9bab-c3cb7f10056a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_fbe6f7b3-0b73-4414-8866-e103ed69208f" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_adba6f7f-5472-4061-9bab-c3cb7f10056a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_adba6f7f-5472-4061-9bab-c3cb7f10056a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_adba6f7f-5472-4061-9bab-c3cb7f10056a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_adba6f7f-5472-4061-9bab-c3cb7f10056a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5ea1788e-390b-44d4-8a20-dc6311d7eee0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_adba6f7f-5472-4061-9bab-c3cb7f10056a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5ea1788e-390b-44d4-8a20-dc6311d7eee0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_94049a53-445f-4b41-b094-b849867f3f5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5ea1788e-390b-44d4-8a20-dc6311d7eee0" xlink:to="loc_us-gaap_SeniorNotesMember_94049a53-445f-4b41-b094-b849867f3f5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_5cb6faeb-4740-4322-823c-8f19c0a37540" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_5cb6faeb-4740-4322-823c-8f19c0a37540" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_eca67247-867b-4be0-8ab2-09becdefb049" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_eca67247-867b-4be0-8ab2-09becdefb049" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_b0545393-fe90-4266-b173-75aabdbf32d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_b0545393-fe90-4266-b173-75aabdbf32d6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSeniorDebt_1cd24e1a-94fd-456d-a43a-8375b58e5567" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_RepaymentsOfSeniorDebt_1cd24e1a-94fd-456d-a43a-8375b58e5567" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PaymentOfDebtAccruedInterest_8c2a4d71-b205-45e5-89f2-60bf145488ef" xlink:href="nrg-20231231.xsd#nrg_PaymentOfDebtAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_nrg_PaymentOfDebtAccruedInterest_8c2a4d71-b205-45e5-89f2-60bf145488ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_345eceb4-a098-4d5d-97c8-000506980f0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_345eceb4-a098-4d5d-97c8-000506980f0b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_edf6f30f-de4d-450d-ab57-f4f0104f0266" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_edf6f30f-de4d-450d-ab57-f4f0104f0266" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_e59b9996-ab01-405c-8a43-32449a086a7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_582ce40b-8cb9-4cbb-8c5b-a554aef1281c" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_e59b9996-ab01-405c-8a43-32449a086a7e" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesRedemptionsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesSeniorNotesRedemptionsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesRedemptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_df2b600b-61c2-4099-a4f0-2f02c26adc8e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_51a85260-7da2-4865-a8b3-8d915991c769" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_df2b600b-61c2-4099-a4f0-2f02c26adc8e" xlink:to="loc_us-gaap_DebtInstrumentTable_51a85260-7da2-4865-a8b3-8d915991c769" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_1067b402-791c-4b49-8a41-009a46bf09b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_51a85260-7da2-4865-a8b3-8d915991c769" xlink:to="loc_us-gaap_DebtInstrumentAxis_1067b402-791c-4b49-8a41-009a46bf09b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_1067b402-791c-4b49-8a41-009a46bf09b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_1067b402-791c-4b49-8a41-009a46bf09b7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_1067b402-791c-4b49-8a41-009a46bf09b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c75e1df7-0419-4f0e-8329-bda475039018" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_1067b402-791c-4b49-8a41-009a46bf09b7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c75e1df7-0419-4f0e-8329-bda475039018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2026Member_b22ad5a1-b80a-4fc1-90b6-c239ca4721c1" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_c75e1df7-0419-4f0e-8329-bda475039018" xlink:to="loc_nrg_SeniorNotesdue2026Member_b22ad5a1-b80a-4fc1-90b6-c239ca4721c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2027Member_b81b880e-dbfb-42d5-ae32-a77ffcdf4758" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_c75e1df7-0419-4f0e-8329-bda475039018" xlink:to="loc_nrg_SeniorNotesdue2027Member_b81b880e-dbfb-42d5-ae32-a77ffcdf4758" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_d3fb18f2-7d4e-4df6-a0e1-89d9d6daa214" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_df2b600b-61c2-4099-a4f0-2f02c26adc8e" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_d3fb18f2-7d4e-4df6-a0e1-89d9d6daa214" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_efd9d8bb-a762-45dd-b0e0-3072401ec306" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRepurchasedFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_df2b600b-61c2-4099-a4f0-2f02c26adc8e" xlink:to="loc_us-gaap_DebtInstrumentRepurchasedFaceAmount_efd9d8bb-a762-45dd-b0e0-3072401ec306" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSeniorDebt_f7624f36-7a30-4cf1-af25-ff0dc0ccf16c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_df2b600b-61c2-4099-a4f0-2f02c26adc8e" xlink:to="loc_us-gaap_RepaymentsOfSeniorDebt_f7624f36-7a30-4cf1-af25-ff0dc0ccf16c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_7826a429-f2fb-487a-a690-77a106191a5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_df2b600b-61c2-4099-a4f0-2f02c26adc8e" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_7826a429-f2fb-487a-a690-77a106191a5d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPayableCurrent_62f4761e-3e3f-4ed4-a347-3531832df6e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_df2b600b-61c2-4099-a4f0-2f02c26adc8e" xlink:to="loc_us-gaap_InterestPayableCurrent_62f4761e-3e3f-4ed4-a347-3531832df6e2" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesIssuanceofConvertibleSeniorNotesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesIssuanceofConvertibleSeniorNotesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesIssuanceofConvertibleSeniorNotesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_6fa777cd-4d53-49e1-abbb-547f6286ed67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentTable_6fa777cd-4d53-49e1-abbb-547f6286ed67" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_5cb73e9c-3a43-40b9-972e-5642ae015d45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6fa777cd-4d53-49e1-abbb-547f6286ed67" xlink:to="loc_us-gaap_DebtInstrumentAxis_5cb73e9c-3a43-40b9-972e-5642ae015d45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5cb73e9c-3a43-40b9-972e-5642ae015d45_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_5cb73e9c-3a43-40b9-972e-5642ae015d45" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5cb73e9c-3a43-40b9-972e-5642ae015d45_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_987fcaec-07f5-47b7-a077-e41d3eff35cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_5cb73e9c-3a43-40b9-972e-5642ae015d45" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_987fcaec-07f5-47b7-a077-e41d3eff35cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConvertibleSeniorNotesDue2048Member_02e562aa-8663-480f-898e-670e5e7cd0d0" xlink:href="nrg-20231231.xsd#nrg_ConvertibleSeniorNotesDue2048Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_987fcaec-07f5-47b7-a077-e41d3eff35cf" xlink:to="loc_nrg_ConvertibleSeniorNotesDue2048Member_02e562aa-8663-480f-898e-670e5e7cd0d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_f56b16ac-2f95-4589-a47e-e51b3a6dad7c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6fa777cd-4d53-49e1-abbb-547f6286ed67" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_f56b16ac-2f95-4589-a47e-e51b3a6dad7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f56b16ac-2f95-4589-a47e-e51b3a6dad7c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f56b16ac-2f95-4589-a47e-e51b3a6dad7c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f56b16ac-2f95-4589-a47e-e51b3a6dad7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_dafbb768-e495-499f-a414-33f8dc17ae1b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f56b16ac-2f95-4589-a47e-e51b3a6dad7c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_dafbb768-e495-499f-a414-33f8dc17ae1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RecourseDebtMember_006da686-647b-499f-bb1e-740a779945a4" xlink:href="nrg-20231231.xsd#nrg_RecourseDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_dafbb768-e495-499f-a414-33f8dc17ae1b" xlink:to="loc_nrg_RecourseDebtMember_006da686-647b-499f-bb1e-740a779945a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8ceb82a7-423d-4400-b0ff-d61131de398b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6fa777cd-4d53-49e1-abbb-547f6286ed67" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8ceb82a7-423d-4400-b0ff-d61131de398b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_8ceb82a7-423d-4400-b0ff-d61131de398b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8ceb82a7-423d-4400-b0ff-d61131de398b" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_8ceb82a7-423d-4400-b0ff-d61131de398b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_fb43ee9e-5f08-43e7-b48c-c2d81f2ffbdf" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_8ceb82a7-423d-4400-b0ff-d61131de398b" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_fb43ee9e-5f08-43e7-b48c-c2d81f2ffbdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_97ef976a-201d-4e22-b92c-c1457e7753b3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_fb43ee9e-5f08-43e7-b48c-c2d81f2ffbdf" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_97ef976a-201d-4e22-b92c-c1457e7753b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_70cf64f7-522b-45ed-a6c2-1f62ad42a84d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6fa777cd-4d53-49e1-abbb-547f6286ed67" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_70cf64f7-522b-45ed-a6c2-1f62ad42a84d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_70cf64f7-522b-45ed-a6c2-1f62ad42a84d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_70cf64f7-522b-45ed-a6c2-1f62ad42a84d" xlink:to="loc_us-gaap_EquityComponentDomain_70cf64f7-522b-45ed-a6c2-1f62ad42a84d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_3805bdb1-89f5-464f-81e8-b031133f66f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_70cf64f7-522b-45ed-a6c2-1f62ad42a84d" xlink:to="loc_us-gaap_EquityComponentDomain_3805bdb1-89f5-464f-81e8-b031133f66f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_50a1235f-ae8b-40ec-8b74-5b77594574a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3805bdb1-89f5-464f-81e8-b031133f66f8" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_50a1235f-ae8b-40ec-8b74-5b77594574a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_68952a63-5db1-4fb7-9e5c-b692c2c6874c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3805bdb1-89f5-464f-81e8-b031133f66f8" xlink:to="loc_us-gaap_RetainedEarningsMember_68952a63-5db1-4fb7-9e5c-b692c2c6874c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleRemainingDiscountAmortizationPeriod1_1b7d66a8-f6e0-47fa-9607-2dd1aefb604b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleRemainingDiscountAmortizationPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleRemainingDiscountAmortizationPeriod1_1b7d66a8-f6e0-47fa-9607-2dd1aefb604b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9ecc9f4d-af6d-4650-8155-35c4123521c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9ecc9f4d-af6d-4650-8155-35c4123521c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_00678ebb-3aef-4066-9e18-01f2fa8e9651" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_00678ebb-3aef-4066-9e18-01f2fa8e9651" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_2ca2bcff-8fe2-4d6d-afeb-d92e50d59d7f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_2ca2bcff-8fe2-4d6d-afeb-d92e50d59d7f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_5c03850a-d415-48e0-bd82-f0b26cbb17ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_5c03850a-d415-48e0-bd82-f0b26cbb17ea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_00c47b43-2c00-4fb5-b11e-afeac977c0b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_00c47b43-2c00-4fb5-b11e-afeac977c0b5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent_625e9b73-93ad-4235-aef5-91e4940eac23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent_625e9b73-93ad-4235-aef5-91e4940eac23" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_88846c76-b696-4fcc-83da-cdc93f88d455" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_88846c76-b696-4fcc-83da-cdc93f88d455" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_9efb6265-35d2-41df-b92c-0e8f9a9b8571" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_9efb6265-35d2-41df-b92c-0e8f9a9b8571" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_4fecc560-425e-4b78-b30d-770abc7656e5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_941fa84e-2f77-4f49-bada-a28cfde3e71e" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_4fecc560-425e-4b78-b30d-770abc7656e5" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesInterestExpenseinConnectionwithConvertibleSeniorNotesdue2048Details" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesInterestExpenseinConnectionwithConvertibleSeniorNotesdue2048Details"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesInterestExpenseinConnectionwithConvertibleSeniorNotesdue2048Details" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_7b3e6b7f-5fdc-4675-a1f6-9f12e79cac88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_2c6a7048-1415-41b2-aa7e-8a72f37da13f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7b3e6b7f-5fdc-4675-a1f6-9f12e79cac88" xlink:to="loc_us-gaap_DebtInstrumentTable_2c6a7048-1415-41b2-aa7e-8a72f37da13f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_d1728baa-884f-4581-b007-335b5ec37cfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_2c6a7048-1415-41b2-aa7e-8a72f37da13f" xlink:to="loc_us-gaap_DebtInstrumentAxis_d1728baa-884f-4581-b007-335b5ec37cfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_d1728baa-884f-4581-b007-335b5ec37cfc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_d1728baa-884f-4581-b007-335b5ec37cfc" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_d1728baa-884f-4581-b007-335b5ec37cfc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_973f4284-6a62-448e-82c7-9b7ea0f423e9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_d1728baa-884f-4581-b007-335b5ec37cfc" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_973f4284-6a62-448e-82c7-9b7ea0f423e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ConvertibleSeniorNotesDue2048Member_c82ec8a6-88d4-418d-91c3-a7c7f01da93c" xlink:href="nrg-20231231.xsd#nrg_ConvertibleSeniorNotesDue2048Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_973f4284-6a62-448e-82c7-9b7ea0f423e9" xlink:to="loc_nrg_ConvertibleSeniorNotesDue2048Member_c82ec8a6-88d4-418d-91c3-a7c7f01da93c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_f1bec928-fdad-4f2e-8e41-e098f5617355" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_2c6a7048-1415-41b2-aa7e-8a72f37da13f" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_f1bec928-fdad-4f2e-8e41-e098f5617355" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f1bec928-fdad-4f2e-8e41-e098f5617355_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f1bec928-fdad-4f2e-8e41-e098f5617355" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f1bec928-fdad-4f2e-8e41-e098f5617355_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_bc884752-674e-4746-afc2-63415c399a23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f1bec928-fdad-4f2e-8e41-e098f5617355" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_bc884752-674e-4746-afc2-63415c399a23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RecourseDebtMember_821c679f-0c6e-4d97-8872-54d6d6531088" xlink:href="nrg-20231231.xsd#nrg_RecourseDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bc884752-674e-4746-afc2-63415c399a23" xlink:to="loc_nrg_RecourseDebtMember_821c679f-0c6e-4d97-8872-54d6d6531088" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebtExcludingAmortization_7d97bbea-db20-4e15-aa19-088982c24daa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseDebtExcludingAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7b3e6b7f-5fdc-4675-a1f6-9f12e79cac88" xlink:to="loc_us-gaap_InterestExpenseDebtExcludingAmortization_7d97bbea-db20-4e15-aa19-088982c24daa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_678e9dd2-a09b-4db1-b148-b9684a539bfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7b3e6b7f-5fdc-4675-a1f6-9f12e79cac88" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_678e9dd2-a09b-4db1-b148-b9684a539bfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_f62693b0-b3fd-4b9d-95ff-0f2c865a4557" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7b3e6b7f-5fdc-4675-a1f6-9f12e79cac88" xlink:to="loc_us-gaap_InterestExpenseDebt_f62693b0-b3fd-4b9d-95ff-0f2c865a4557" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_5b4b7742-53c9-4c34-aaa0-17e4a963c577" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7b3e6b7f-5fdc-4675-a1f6-9f12e79cac88" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_5b4b7742-53c9-4c34-aaa0-17e4a963c577" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesOutstandingwithEarlyRedemptionFeaturesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesSeniorNotesOutstandingwithEarlyRedemptionFeaturesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesOutstandingwithEarlyRedemptionFeaturesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_36d6c8cd-041d-45e1-ad77-bff4275560a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_5aa421f5-ac40-4c2d-b061-f52d62ee1a39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_36d6c8cd-041d-45e1-ad77-bff4275560a1" xlink:to="loc_us-gaap_DebtInstrumentTable_5aa421f5-ac40-4c2d-b061-f52d62ee1a39" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_f16ed3e3-224a-46bc-be52-1f9f1ec04759" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5aa421f5-ac40-4c2d-b061-f52d62ee1a39" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_f16ed3e3-224a-46bc-be52-1f9f1ec04759" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f16ed3e3-224a-46bc-be52-1f9f1ec04759_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f16ed3e3-224a-46bc-be52-1f9f1ec04759" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f16ed3e3-224a-46bc-be52-1f9f1ec04759_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_71fd267b-91db-4a88-8279-9084a18ddf21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f16ed3e3-224a-46bc-be52-1f9f1ec04759" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_71fd267b-91db-4a88-8279-9084a18ddf21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RecourseDebtMember_6dc042b0-51e6-4882-8255-c8d91d3a4ddd" xlink:href="nrg-20231231.xsd#nrg_RecourseDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_71fd267b-91db-4a88-8279-9084a18ddf21" xlink:to="loc_nrg_RecourseDebtMember_6dc042b0-51e6-4882-8255-c8d91d3a4ddd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_cee1c30a-8017-4cab-9049-4c2fb1b58b58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5aa421f5-ac40-4c2d-b061-f52d62ee1a39" xlink:to="loc_us-gaap_DebtInstrumentAxis_cee1c30a-8017-4cab-9049-4c2fb1b58b58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_cee1c30a-8017-4cab-9049-4c2fb1b58b58_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_cee1c30a-8017-4cab-9049-4c2fb1b58b58" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_cee1c30a-8017-4cab-9049-4c2fb1b58b58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_cee1c30a-8017-4cab-9049-4c2fb1b58b58" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2027Member_b732ae6d-427f-49f3-a81f-0bcf00950e7f" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:to="loc_nrg_SeniorNotesdue2027Member_b732ae6d-427f-49f3-a81f-0bcf00950e7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2028Member_a3c38e68-4822-43b4-a724-8c61b0745649" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:to="loc_nrg_SeniorNotesdue2028Member_a3c38e68-4822-43b4-a724-8c61b0745649" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A5250SeniorNotesDue2029Member_bef8ee38-746f-4e0a-b48f-1530084c46e2" xlink:href="nrg-20231231.xsd#nrg_A5250SeniorNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:to="loc_nrg_A5250SeniorNotesDue2029Member_bef8ee38-746f-4e0a-b48f-1530084c46e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_17de7f32-4547-40b2-a9bd-1233184ceb7e" xlink:href="nrg-20231231.xsd#nrg_A3375SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:to="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_17de7f32-4547-40b2-a9bd-1233184ceb7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3625SeniorUnsecuredNotesDueFebruary2031Member_0873258c-57fb-49b4-8b56-a7f9ce882d21" xlink:href="nrg-20231231.xsd#nrg_A3625SeniorUnsecuredNotesDueFebruary2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:to="loc_nrg_A3625SeniorUnsecuredNotesDueFebruary2031Member_0873258c-57fb-49b4-8b56-a7f9ce882d21" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3875SeniorNotesDue2032Member_afb16d97-1ef1-4f32-9b61-e8a3a35f1165" xlink:href="nrg-20231231.xsd#nrg_A3875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:to="loc_nrg_A3875SeniorNotesDue2032Member_afb16d97-1ef1-4f32-9b61-e8a3a35f1165" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_35d3f342-2269-44f1-9be7-d0c83c0d1162" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_78d9ca61-5a8f-4149-9d74-4d918844048d" xlink:to="loc_us-gaap_SeniorNotesMember_35d3f342-2269-44f1-9be7-d0c83c0d1162" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_42feef46-e0c1-4480-bb9c-b8488f28b2c5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5aa421f5-ac40-4c2d-b061-f52d62ee1a39" xlink:to="loc_srt_RangeAxis_42feef46-e0c1-4480-bb9c-b8488f28b2c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_42feef46-e0c1-4480-bb9c-b8488f28b2c5_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_42feef46-e0c1-4480-bb9c-b8488f28b2c5" xlink:to="loc_srt_RangeMember_42feef46-e0c1-4480-bb9c-b8488f28b2c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6aa7ca33-5b4b-4ebb-bd0e-ecebb2066540" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_42feef46-e0c1-4480-bb9c-b8488f28b2c5" xlink:to="loc_srt_RangeMember_6aa7ca33-5b4b-4ebb-bd0e-ecebb2066540" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_664fe4fa-8e7f-4ee1-9c15-cb16d8770c30" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6aa7ca33-5b4b-4ebb-bd0e-ecebb2066540" xlink:to="loc_srt_MinimumMember_664fe4fa-8e7f-4ee1-9c15-cb16d8770c30" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_f02a20a3-cba2-43de-ac7d-fc79581f88e2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6aa7ca33-5b4b-4ebb-bd0e-ecebb2066540" xlink:to="loc_srt_MaximumMember_f02a20a3-cba2-43de-ac7d-fc79581f88e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0cc4886d-a0bc-45be-95d8-cb82c4506282" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_36d6c8cd-041d-45e1-ad77-bff4275560a1" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0cc4886d-a0bc-45be-95d8-cb82c4506282" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_450bb262-9c1a-4b16-905b-276177c5646d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_36d6c8cd-041d-45e1-ad77-bff4275560a1" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_450bb262-9c1a-4b16-905b-276177c5646d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesRedemptionPeriodDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesSeniorNotesRedemptionPeriodDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesSeniorNotesRedemptionPeriodDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_0d1bbf78-3a73-4ec6-b3b7-4ec6419279d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_us-gaap_DebtInstrumentTable_0d1bbf78-3a73-4ec6-b3b7-4ec6419279d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_42cd1932-4a2a-40f9-85fc-90bcddb00f8a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0d1bbf78-3a73-4ec6-b3b7-4ec6419279d8" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_42cd1932-4a2a-40f9-85fc-90bcddb00f8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_42cd1932-4a2a-40f9-85fc-90bcddb00f8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_42cd1932-4a2a-40f9-85fc-90bcddb00f8a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_42cd1932-4a2a-40f9-85fc-90bcddb00f8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d07d7901-e0e3-4d56-80be-9cffd6ab63c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_42cd1932-4a2a-40f9-85fc-90bcddb00f8a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d07d7901-e0e3-4d56-80be-9cffd6ab63c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RecourseDebtMember_ddda396a-5ae9-45d0-95c6-5ea1ad1944bf" xlink:href="nrg-20231231.xsd#nrg_RecourseDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d07d7901-e0e3-4d56-80be-9cffd6ab63c9" xlink:to="loc_nrg_RecourseDebtMember_ddda396a-5ae9-45d0-95c6-5ea1ad1944bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_bc53efe4-6119-43d9-92fe-9bc407257aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0d1bbf78-3a73-4ec6-b3b7-4ec6419279d8" xlink:to="loc_us-gaap_DebtInstrumentAxis_bc53efe4-6119-43d9-92fe-9bc407257aeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_bc53efe4-6119-43d9-92fe-9bc407257aeb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_bc53efe4-6119-43d9-92fe-9bc407257aeb" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_bc53efe4-6119-43d9-92fe-9bc407257aeb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_bc53efe4-6119-43d9-92fe-9bc407257aeb" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2027Member_5102fac5-3993-48be-b6d8-bbf4fdc84d2e" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:to="loc_nrg_SeniorNotesdue2027Member_5102fac5-3993-48be-b6d8-bbf4fdc84d2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorNotesdue2028Member_d0a6d34b-8910-4205-a800-e6f68caf7f47" xlink:href="nrg-20231231.xsd#nrg_SeniorNotesdue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:to="loc_nrg_SeniorNotesdue2028Member_d0a6d34b-8910-4205-a800-e6f68caf7f47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A5250SeniorNotesDue2029Member_e568827b-9b57-4b2a-9c03-19b8ea85c861" xlink:href="nrg-20231231.xsd#nrg_A5250SeniorNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:to="loc_nrg_A5250SeniorNotesDue2029Member_e568827b-9b57-4b2a-9c03-19b8ea85c861" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_269baa2d-7055-4f1f-8089-4c498047c8b3" xlink:href="nrg-20231231.xsd#nrg_A3375SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:to="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_269baa2d-7055-4f1f-8089-4c498047c8b3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3625SeniorUnsecuredNotesDueFebruary2031Member_e8e8ddbf-9c8b-46ab-bd43-0a8145a0c09d" xlink:href="nrg-20231231.xsd#nrg_A3625SeniorUnsecuredNotesDueFebruary2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:to="loc_nrg_A3625SeniorUnsecuredNotesDueFebruary2031Member_e8e8ddbf-9c8b-46ab-bd43-0a8145a0c09d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3875SeniorNotesDue2032Member_4a8a3abe-ce02-40c2-a52a-bcf43fa5706f" xlink:href="nrg-20231231.xsd#nrg_A3875SeniorNotesDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_88f81725-d793-4e4e-b763-3751c684df6a" xlink:to="loc_nrg_A3875SeniorNotesDue2032Member_4a8a3abe-ce02-40c2-a52a-bcf43fa5706f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_472f43ec-9d7f-480a-8620-9235af2ad4ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0d1bbf78-3a73-4ec6-b3b7-4ec6419279d8" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_472f43ec-9d7f-480a-8620-9235af2ad4ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_472f43ec-9d7f-480a-8620-9235af2ad4ab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_472f43ec-9d7f-480a-8620-9235af2ad4ab" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_472f43ec-9d7f-480a-8620-9235af2ad4ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_472f43ec-9d7f-480a-8620-9235af2ad4ab" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15July2023to14July2024Member_5618479e-6114-4be0-a27f-59a13738b8c9" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15July2023to14July2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15July2023to14July2024Member_5618479e-6114-4be0-a27f-59a13738b8c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15July2024AndThereafterMember_fe65777f-08ea-4228-a0ad-7618eb1fb985" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15July2024AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15July2024AndThereafterMember_fe65777f-08ea-4228-a0ad-7618eb1fb985" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15January2024to14January2025Member_1cb2678f-af93-4079-8e92-5a87cf515f9f" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15January2024to14January2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15January2024to14January2025Member_1cb2678f-af93-4079-8e92-5a87cf515f9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15January2025to14January2026Member_9e39f3b8-6b2d-4d91-a3cc-bf716667a877" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15January2025to14January2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15January2025to14January2026Member_9e39f3b8-6b2d-4d91-a3cc-bf716667a877" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15January2026AndThereafterMember_9edb8f2a-5218-4617-b910-39ebede53e28" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15January2026AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15January2026AndThereafterMember_9edb8f2a-5218-4617-b910-39ebede53e28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodPriorToJune152024Member_bf328d4b-f24c-4b62-b70d-d7e89923c96f" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodPriorToJune152024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodPriorToJune152024Member_bf328d4b-f24c-4b62-b70d-d7e89923c96f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15June2024To14June2025Member_ab15ac80-d036-4ddc-a18e-581b4a6b392e" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15June2024To14June2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15June2024To14June2025Member_ab15ac80-d036-4ddc-a18e-581b4a6b392e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15June2025To14June2026Member_f5ae37d8-4217-4996-bde0-8ca6dee6842b" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15June2025To14June2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15June2025To14June2026Member_f5ae37d8-4217-4996-bde0-8ca6dee6842b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFrom15June2026To14June2027Member_63c2ac4c-95bd-43cd-8658-9c9b08b1b508" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFrom15June2026To14June2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFrom15June2026To14June2027Member_63c2ac4c-95bd-43cd-8658-9c9b08b1b508" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFromJune152027AndThereafterMember_bfa529af-82de-4c91-b192-76f56ff2ead6" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFromJune152027AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFromJune152027AndThereafterMember_bfa529af-82de-4c91-b192-76f56ff2ead6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152024ToFebruary142025Member_dcc19ee0-4c77-4f92-9f58-ec27e99d457a" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152024ToFebruary142025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFebruary152024ToFebruary142025Member_dcc19ee0-4c77-4f92-9f58-ec27e99d457a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152025ToFebruary142026Member_2b6bf7e7-8ad8-476a-b576-2da272bc8f8b" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152025ToFebruary142026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFebruary152025ToFebruary142026Member_2b6bf7e7-8ad8-476a-b576-2da272bc8f8b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152026AndThereafterMember_bc925cde-1722-496c-b378-ad63bb019d04" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152026AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFebruary152026AndThereafterMember_bc925cde-1722-496c-b378-ad63bb019d04" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodPriorToFebruary152026Member_7866fcae-99d5-4bc5-9a48-65906e10fa32" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodPriorToFebruary152026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodPriorToFebruary152026Member_7866fcae-99d5-4bc5-9a48-65906e10fa32" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152026ToFebruary142027Member_6027fba6-6aa2-4a24-bb59-6b2ad6f60df5" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152026ToFebruary142027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFebruary152026ToFebruary142027Member_6027fba6-6aa2-4a24-bb59-6b2ad6f60df5" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152027ToFebruary142028Member_9464234f-74bb-4a90-80a9-f706990e838f" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152027ToFebruary142028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFebruary152027ToFebruary142028Member_9464234f-74bb-4a90-80a9-f706990e838f" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152028ToFebruary142029Member_b8416bdb-768b-4ee1-a880-b4b1287241ee" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152028ToFebruary142029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFebruary152028ToFebruary142029Member_b8416bdb-768b-4ee1-a880-b4b1287241ee" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152029AndThereafterMember_f82a26f2-f6cf-4ed7-96db-53a7ae0d97f7" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152029AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodFebruary152029AndThereafterMember_f82a26f2-f6cf-4ed7-96db-53a7ae0d97f7" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodPriorToAugust152024Member_a06ff79e-1a90-48a4-9c99-896a0471fcce" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodPriorToAugust152024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodPriorToAugust152024Member_a06ff79e-1a90-48a4-9c99-896a0471fcce" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodPriorToFebruary152027Member_e18518ef-ae23-4004-860b-71703c4d5bce" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodPriorToFebruary152027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_RedemptionPeriodPriorToFebruary152027Member_e18518ef-ae23-4004-860b-71703c4d5bce" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A12MonthsBeginningFebruary152027Member_2079ad81-bc50-4676-a4a3-0a0aff878b0a" xlink:href="nrg-20231231.xsd#nrg_A12MonthsBeginningFebruary152027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_A12MonthsBeginningFebruary152027Member_2079ad81-bc50-4676-a4a3-0a0aff878b0a" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A12MonthsBeginningFebruary152028Member_2d44e8b7-a566-4125-803a-491dfd5565c0" xlink:href="nrg-20231231.xsd#nrg_A12MonthsBeginningFebruary152028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_A12MonthsBeginningFebruary152028Member_2d44e8b7-a566-4125-803a-491dfd5565c0" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A12MonthsBeginningFebruary152029Member_6a56f1a8-784f-4a3f-a83c-f8966ebd166e" xlink:href="nrg-20231231.xsd#nrg_A12MonthsBeginningFebruary152029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_A12MonthsBeginningFebruary152029Member_6a56f1a8-784f-4a3f-a83c-f8966ebd166e" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A12MonthsBeginningFebruary152030AndThereafterMember_2157e2d4-9bf4-4d03-9871-a0afffe9eb34" xlink:href="nrg-20231231.xsd#nrg_A12MonthsBeginningFebruary152030AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_316eed65-25dc-4119-8e14-75403ac5d987" xlink:to="loc_nrg_A12MonthsBeginningFebruary152030AndThereafterMember_2157e2d4-9bf4-4d03-9871-a0afffe9eb34" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_599f7a2b-22ca-4563-b24e-30c6a7ef4096" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0d1bbf78-3a73-4ec6-b3b7-4ec6419279d8" xlink:to="loc_us-gaap_VariableRateAxis_599f7a2b-22ca-4563-b24e-30c6a7ef4096" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_599f7a2b-22ca-4563-b24e-30c6a7ef4096_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_599f7a2b-22ca-4563-b24e-30c6a7ef4096" xlink:to="loc_us-gaap_VariableRateDomain_599f7a2b-22ca-4563-b24e-30c6a7ef4096_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_2410ab9e-8a08-4ef1-81fd-2ebe83e324c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_599f7a2b-22ca-4563-b24e-30c6a7ef4096" xlink:to="loc_us-gaap_VariableRateDomain_2410ab9e-8a08-4ef1-81fd-2ebe83e324c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TreasuryRateMember_69e5abf7-53c3-46b0-b9a9-b0ce38096b77" xlink:href="nrg-20231231.xsd#nrg_TreasuryRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_2410ab9e-8a08-4ef1-81fd-2ebe83e324c9" xlink:to="loc_nrg_TreasuryRateMember_69e5abf7-53c3-46b0-b9a9-b0ce38096b77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_e7034a75-21b2-4ac3-b1f5-d173732cdd46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_e7034a75-21b2-4ac3-b1f5-d173732cdd46" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_dbbab8dd-bcfe-4dff-a565-05a0392a7551" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_dbbab8dd-bcfe-4dff-a565-05a0392a7551" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PremiumPercentageOfPrincipalOfSeniorNotesDiscountFactor_04d4d7e2-8baf-4130-b410-8269321133c3" xlink:href="nrg-20231231.xsd#nrg_PremiumPercentageOfPrincipalOfSeniorNotesDiscountFactor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_nrg_PremiumPercentageOfPrincipalOfSeniorNotesDiscountFactor_04d4d7e2-8baf-4130-b410-8269321133c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DebtInstrumentPresentValueOfNoteRate_8320ec8d-a3a4-4fe2-ab9b-a5b8f6088667" xlink:href="nrg-20231231.xsd#nrg_DebtInstrumentPresentValueOfNoteRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_nrg_DebtInstrumentPresentValueOfNoteRate_8320ec8d-a3a4-4fe2-ab9b-a5b8f6088667" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_181e20e3-99b4-46b7-b8bf-eebd82f847ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_181e20e3-99b4-46b7-b8bf-eebd82f847ab" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DebtInstrumentOutstandingAmountAfterRedemptionPercentage_d27e53b8-c4e9-45cb-a967-ff51ecfb7f19" xlink:href="nrg-20231231.xsd#nrg_DebtInstrumentOutstandingAmountAfterRedemptionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_nrg_DebtInstrumentOutstandingAmountAfterRedemptionPercentage_d27e53b8-c4e9-45cb-a967-ff51ecfb7f19" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DebtInstrumentRedemptionPricePercentageSustainabilityPerformanceTargetSatisfiedAndConfirmedByExternalVerifier_85ea2238-9dfe-45e2-b62b-5c178e48bf76" xlink:href="nrg-20231231.xsd#nrg_DebtInstrumentRedemptionPricePercentageSustainabilityPerformanceTargetSatisfiedAndConfirmedByExternalVerifier"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_nrg_DebtInstrumentRedemptionPricePercentageSustainabilityPerformanceTargetSatisfiedAndConfirmedByExternalVerifier_85ea2238-9dfe-45e2-b62b-5c178e48bf76" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DebtInstrumentRedemptionPricePercentageSustainabilityPerformanceTargetNotSatisfiedAndorConfirmedByExternalVerifier_53424c57-a1d3-4c5d-9db4-590ef7d79ec1" xlink:href="nrg-20231231.xsd#nrg_DebtInstrumentRedemptionPricePercentageSustainabilityPerformanceTargetNotSatisfiedAndorConfirmedByExternalVerifier"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_b61958b4-a6a6-4c67-8fef-23097410451f" xlink:to="loc_nrg_DebtInstrumentRedemptionPricePercentageSustainabilityPerformanceTargetNotSatisfiedAndorConfirmedByExternalVerifier_53424c57-a1d3-4c5d-9db4-590ef7d79ec1" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesReceivablesSecuritizationsandRepurchaseFacilityDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesReceivablesSecuritizationsandRepurchaseFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesReceivablesSecuritizationsandRepurchaseFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_d9b28d9b-178c-4eb2-ae63-8f4314f8d6af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:to="loc_us-gaap_DebtInstrumentTable_d9b28d9b-178c-4eb2-ae63-8f4314f8d6af" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_60fc28ee-10c8-48a1-8623-fd3b1be3bf38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9b28d9b-178c-4eb2-ae63-8f4314f8d6af" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_60fc28ee-10c8-48a1-8623-fd3b1be3bf38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_60fc28ee-10c8-48a1-8623-fd3b1be3bf38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_60fc28ee-10c8-48a1-8623-fd3b1be3bf38" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_60fc28ee-10c8-48a1-8623-fd3b1be3bf38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_23c2a9d5-9f08-4def-8e20-3bc08dcf779d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_60fc28ee-10c8-48a1-8623-fd3b1be3bf38" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_23c2a9d5-9f08-4def-8e20-3bc08dcf779d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_f4ffbcd5-0d69-459a-bc54-120bab3e0edb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_23c2a9d5-9f08-4def-8e20-3bc08dcf779d" xlink:to="loc_us-gaap_SecuredDebtMember_f4ffbcd5-0d69-459a-bc54-120bab3e0edb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_e3d50277-10f9-4a90-a14b-70456c3675e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9b28d9b-178c-4eb2-ae63-8f4314f8d6af" xlink:to="loc_us-gaap_DebtInstrumentAxis_e3d50277-10f9-4a90-a14b-70456c3675e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_e3d50277-10f9-4a90-a14b-70456c3675e2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_e3d50277-10f9-4a90-a14b-70456c3675e2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_e3d50277-10f9-4a90-a14b-70456c3675e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_f09ce8a8-49c0-4ead-9976-efa168545cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_e3d50277-10f9-4a90-a14b-70456c3675e2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_f09ce8a8-49c0-4ead-9976-efa168545cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ReceivablesFacilityMember_569b1d22-f3ed-4b29-be16-4d4fd1563cb1" xlink:href="nrg-20231231.xsd#nrg_ReceivablesFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f09ce8a8-49c0-4ead-9976-efa168545cbc" xlink:to="loc_nrg_ReceivablesFacilityMember_569b1d22-f3ed-4b29-be16-4d4fd1563cb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RepurchaseFacilityMember_623d63b1-cf70-43aa-bf12-da9bc85ec841" xlink:href="nrg-20231231.xsd#nrg_RepurchaseFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f09ce8a8-49c0-4ead-9976-efa168545cbc" xlink:to="loc_nrg_RepurchaseFacilityMember_623d63b1-cf70-43aa-bf12-da9bc85ec841" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_ad8ca805-531d-4bb5-a06f-26c0e70a66e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9b28d9b-178c-4eb2-ae63-8f4314f8d6af" xlink:to="loc_us-gaap_CreditFacilityAxis_ad8ca805-531d-4bb5-a06f-26c0e70a66e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_ad8ca805-531d-4bb5-a06f-26c0e70a66e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_ad8ca805-531d-4bb5-a06f-26c0e70a66e4" xlink:to="loc_us-gaap_CreditFacilityDomain_ad8ca805-531d-4bb5-a06f-26c0e70a66e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_35024e73-92a6-4847-884d-d23e69a07886" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_ad8ca805-531d-4bb5-a06f-26c0e70a66e4" xlink:to="loc_us-gaap_CreditFacilityDomain_35024e73-92a6-4847-884d-d23e69a07886" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_342353e3-2a69-44fc-9a65-f66f3406f93e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_35024e73-92a6-4847-884d-d23e69a07886" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_342353e3-2a69-44fc-9a65-f66f3406f93e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_0a9687e5-d408-484d-a977-fd65a56c27c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_35024e73-92a6-4847-884d-d23e69a07886" xlink:to="loc_us-gaap_LetterOfCreditMember_0a9687e5-d408-484d-a977-fd65a56c27c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_1cf5443b-ab0c-4879-85b0-43bf8d7f412b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9b28d9b-178c-4eb2-ae63-8f4314f8d6af" xlink:to="loc_us-gaap_VariableRateAxis_1cf5443b-ab0c-4879-85b0-43bf8d7f412b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_1cf5443b-ab0c-4879-85b0-43bf8d7f412b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_1cf5443b-ab0c-4879-85b0-43bf8d7f412b" xlink:to="loc_us-gaap_VariableRateDomain_1cf5443b-ab0c-4879-85b0-43bf8d7f412b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_b9f39452-0f33-4723-ae57-4806e05d5519" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_1cf5443b-ab0c-4879-85b0-43bf8d7f412b" xlink:to="loc_us-gaap_VariableRateDomain_b9f39452-0f33-4723-ae57-4806e05d5519" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_56c64e60-ddec-4cba-b2c4-ba5f37703846" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_b9f39452-0f33-4723-ae57-4806e05d5519" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_56c64e60-ddec-4cba-b2c4-ba5f37703846" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_5de7e309-b8de-4c4b-91f0-f52db4f62cdf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_5de7e309-b8de-4c4b-91f0-f52db4f62cdf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_2993779e-7791-43f1-b4dd-0fdec6081a74" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_2993779e-7791-43f1-b4dd-0fdec6081a74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditCurrent_47f9d828-9e39-424b-8436-4867efcc6894" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LinesOfCreditCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:to="loc_us-gaap_LinesOfCreditCurrent_47f9d828-9e39-424b-8436-4867efcc6894" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_28e3fc51-5c37-4299-9c06-5ae1f91dabda" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_28e3fc51-5c37-4299-9c06-5ae1f91dabda" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeeAmount_72028ed6-e28e-4f0f-9a04-d088ae86d461" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityCommitmentFeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeeAmount_72028ed6-e28e-4f0f-9a04-d088ae86d461" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_7449a5c1-8b72-4544-ab60-2ca09ebcbccd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e06acbe-931f-4786-91be-74718707d043" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_7449a5c1-8b72-4544-ab60-2ca09ebcbccd" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesBilateralLetterofCreditFacilitiesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesBilateralLetterofCreditFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesBilateralLetterofCreditFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_48ac9c1f-c60c-4f83-baff-25600c3d3751" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_2cfa7ffc-4543-49a1-a432-bd67e6a1c5b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_48ac9c1f-c60c-4f83-baff-25600c3d3751" xlink:to="loc_us-gaap_DebtInstrumentTable_2cfa7ffc-4543-49a1-a432-bd67e6a1c5b1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_a7a6a634-9a5d-48bf-9a61-a7990072e5ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_2cfa7ffc-4543-49a1-a432-bd67e6a1c5b1" xlink:to="loc_us-gaap_DebtInstrumentAxis_a7a6a634-9a5d-48bf-9a61-a7990072e5ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_a7a6a634-9a5d-48bf-9a61-a7990072e5ce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_a7a6a634-9a5d-48bf-9a61-a7990072e5ce" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_a7a6a634-9a5d-48bf-9a61-a7990072e5ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7efcc953-c3f9-4e98-a091-8ea5b494c0ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_a7a6a634-9a5d-48bf-9a61-a7990072e5ce" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7efcc953-c3f9-4e98-a091-8ea5b494c0ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_BilateralLetterOfCreditFacilitiesMember_9015c181-8a0d-4c59-a52d-d5ac243e07b2" xlink:href="nrg-20231231.xsd#nrg_BilateralLetterOfCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_7efcc953-c3f9-4e98-a091-8ea5b494c0ac" xlink:to="loc_nrg_BilateralLetterOfCreditFacilitiesMember_9015c181-8a0d-4c59-a52d-d5ac243e07b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_982f61c7-15a8-4190-8566-a84460e4640f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_2cfa7ffc-4543-49a1-a432-bd67e6a1c5b1" xlink:to="loc_us-gaap_CreditFacilityAxis_982f61c7-15a8-4190-8566-a84460e4640f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_982f61c7-15a8-4190-8566-a84460e4640f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_982f61c7-15a8-4190-8566-a84460e4640f" xlink:to="loc_us-gaap_CreditFacilityDomain_982f61c7-15a8-4190-8566-a84460e4640f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_8da973a8-3e5f-462f-a43c-af9c3fdc36ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_982f61c7-15a8-4190-8566-a84460e4640f" xlink:to="loc_us-gaap_CreditFacilityDomain_8da973a8-3e5f-462f-a43c-af9c3fdc36ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_b8aa62ed-b362-4229-a674-c9269a49f67b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_8da973a8-3e5f-462f-a43c-af9c3fdc36ca" xlink:to="loc_us-gaap_LetterOfCreditMember_b8aa62ed-b362-4229-a674-c9269a49f67b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_501a8427-3659-457a-a059-ab194d3fc1d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_2cfa7ffc-4543-49a1-a432-bd67e6a1c5b1" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_501a8427-3659-457a-a059-ab194d3fc1d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_501a8427-3659-457a-a059-ab194d3fc1d7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_501a8427-3659-457a-a059-ab194d3fc1d7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_501a8427-3659-457a-a059-ab194d3fc1d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_dc6b4880-0e87-48be-9c73-1819d36c118d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_501a8427-3659-457a-a059-ab194d3fc1d7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_dc6b4880-0e87-48be-9c73-1819d36c118d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_9185dc59-624b-41f0-a95f-92c8d4f0e94b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_dc6b4880-0e87-48be-9c73-1819d36c118d" xlink:to="loc_us-gaap_SecuredDebtMember_9185dc59-624b-41f0-a95f-92c8d4f0e94b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity_bfe71035-9612-4e87-aa21-c48eac5abda1" xlink:href="nrg-20231231.xsd#nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_48ac9c1f-c60c-4f83-baff-25600c3d3751" xlink:to="loc_nrg_LineOfCreditFacilityIncreaseInBorrowingCapacity_bfe71035-9612-4e87-aa21-c48eac5abda1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8d703436-c657-48ea-8e27-7e840a182851" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_48ac9c1f-c60c-4f83-baff-25600c3d3751" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8d703436-c657-48ea-8e27-7e840a182851" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_162108b5-0485-43d8-a31d-c4474b978e39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_48ac9c1f-c60c-4f83-baff-25600c3d3751" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_162108b5-0485-43d8-a31d-c4474b978e39" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesTaxExemptBondsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesTaxExemptBondsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesTaxExemptBondsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_1b10d544-0b36-4eed-996f-4a8625fc8661" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_84fd0255-31d9-4024-be35-33b90ff06fe9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b10d544-0b36-4eed-996f-4a8625fc8661" xlink:to="loc_us-gaap_DebtInstrumentTable_84fd0255-31d9-4024-be35-33b90ff06fe9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_ab167459-f04d-44ff-aedd-6fe10351549c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_84fd0255-31d9-4024-be35-33b90ff06fe9" xlink:to="loc_us-gaap_DebtInstrumentAxis_ab167459-f04d-44ff-aedd-6fe10351549c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_ab167459-f04d-44ff-aedd-6fe10351549c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_ab167459-f04d-44ff-aedd-6fe10351549c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_ab167459-f04d-44ff-aedd-6fe10351549c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_ab167459-f04d-44ff-aedd-6fe10351549c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_IndianRiverPower2020TaxExemptBondsDue2040Member_ea5ba223-346e-4ddf-9fc8-34b0f016f80e" xlink:href="nrg-20231231.xsd#nrg_IndianRiverPower2020TaxExemptBondsDue2040Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:to="loc_nrg_IndianRiverPower2020TaxExemptBondsDue2040Member_ea5ba223-346e-4ddf-9fc8-34b0f016f80e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_IndianRiverPower2020TaxExemptBondsDue2045Member_68bc6804-5b24-4df0-9fa0-7c2d3d1c4354" xlink:href="nrg-20231231.xsd#nrg_IndianRiverPower2020TaxExemptBondsDue2045Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:to="loc_nrg_IndianRiverPower2020TaxExemptBondsDue2045Member_68bc6804-5b24-4df0-9fa0-7c2d3d1c4354" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NRGDunkirk2020TaxExemptBondsDue2042Member_5b5ffc37-f272-4883-8ce5-196184ee1474" xlink:href="nrg-20231231.xsd#nrg_NRGDunkirk2020TaxExemptBondsDue2042Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:to="loc_nrg_NRGDunkirk2020TaxExemptBondsDue2042Member_5b5ffc37-f272-4883-8ce5-196184ee1474" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FortBendCountytaxexemptbondsdue2045Member_3270f5f3-8637-4c1a-8537-d2b1034bbd35" xlink:href="nrg-20231231.xsd#nrg_FortBendCountytaxexemptbondsdue2045Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:to="loc_nrg_FortBendCountytaxexemptbondsdue2045Member_3270f5f3-8637-4c1a-8537-d2b1034bbd35" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FortBendCountytaxexemptbondsdue2038Member_19c8319c-853e-43a4-8ddb-f8a3c7d5952d" xlink:href="nrg-20231231.xsd#nrg_FortBendCountytaxexemptbondsdue2038Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:to="loc_nrg_FortBendCountytaxexemptbondsdue2038Member_19c8319c-853e-43a4-8ddb-f8a3c7d5952d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FortBendCountytaxexemptbondsdue2042Member_e6a7a1cd-3b29-41fd-b252-695417204c98" xlink:href="nrg-20231231.xsd#nrg_FortBendCountytaxexemptbondsdue2042Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:to="loc_nrg_FortBendCountytaxexemptbondsdue2042Member_e6a7a1cd-3b29-41fd-b252-695417204c98" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TaxexemptBondsMember_df8d6623-49cc-4e0e-b0b7-23158575bfdb" xlink:href="nrg-20231231.xsd#nrg_TaxexemptBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5c4e3df2-f811-4292-b699-2f0cf98dff10" xlink:to="loc_nrg_TaxexemptBondsMember_df8d6623-49cc-4e0e-b0b7-23158575bfdb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_94c84ed7-5d02-4f36-ad16-8e58ee2ba663" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b10d544-0b36-4eed-996f-4a8625fc8661" xlink:to="loc_us-gaap_LongTermDebt_94c84ed7-5d02-4f36-ad16-8e58ee2ba663" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_5b127b8b-7291-4c4b-b84f-7088284e1e25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b10d544-0b36-4eed-996f-4a8625fc8661" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_5b127b8b-7291-4c4b-b84f-7088284e1e25" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesDunkirkBondsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesDunkirkBondsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesDunkirkBondsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_f0e770e4-8e09-4114-bae0-397bc4ad2692" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_75072fdb-4485-471a-9a11-ec18d2acb1d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f0e770e4-8e09-4114-bae0-397bc4ad2692" xlink:to="loc_us-gaap_DebtInstrumentTable_75072fdb-4485-471a-9a11-ec18d2acb1d7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_64b09db0-1561-4ad3-83a5-fb4e5b0045b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_75072fdb-4485-471a-9a11-ec18d2acb1d7" xlink:to="loc_us-gaap_DebtInstrumentAxis_64b09db0-1561-4ad3-83a5-fb4e5b0045b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_64b09db0-1561-4ad3-83a5-fb4e5b0045b9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_64b09db0-1561-4ad3-83a5-fb4e5b0045b9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_64b09db0-1561-4ad3-83a5-fb4e5b0045b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_339d6d93-9a13-4db9-bc64-fb1705079589" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_64b09db0-1561-4ad3-83a5-fb4e5b0045b9" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_339d6d93-9a13-4db9-bc64-fb1705079589" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DunkirkBondsMember_5ef0d1ca-5afd-4b05-aad3-ecfa7a40dfca" xlink:href="nrg-20231231.xsd#nrg_DunkirkBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_339d6d93-9a13-4db9-bc64-fb1705079589" xlink:to="loc_nrg_DunkirkBondsMember_5ef0d1ca-5afd-4b05-aad3-ecfa7a40dfca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_d1dc6e53-231b-48c0-bc58-95074be26908" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f0e770e4-8e09-4114-bae0-397bc4ad2692" xlink:to="loc_us-gaap_LongTermDebt_d1dc6e53-231b-48c0-bc58-95074be26908" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_25b32f5f-eab8-432b-bc09-5e3aa1e0ce64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_f0e770e4-8e09-4114-bae0-397bc4ad2692" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_25b32f5f-eab8-432b-bc09-5e3aa1e0ce64" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesPreCapitalizedTrustSecuritiesFacilityDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesPreCapitalizedTrustSecuritiesFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesPreCapitalizedTrustSecuritiesFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_1d5d05bc-8308-48b0-94ea-8c195c724f59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:to="loc_us-gaap_DebtInstrumentTable_1d5d05bc-8308-48b0-94ea-8c195c724f59" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_94151899-0e38-4359-8f20-3b25e1a9c29e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1d5d05bc-8308-48b0-94ea-8c195c724f59" xlink:to="loc_us-gaap_FinancialInstrumentAxis_94151899-0e38-4359-8f20-3b25e1a9c29e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_94151899-0e38-4359-8f20-3b25e1a9c29e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_94151899-0e38-4359-8f20-3b25e1a9c29e" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_94151899-0e38-4359-8f20-3b25e1a9c29e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cee6cf81-c2ff-4d53-a66a-45752614c908" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_94151899-0e38-4359-8f20-3b25e1a9c29e" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cee6cf81-c2ff-4d53-a66a-45752614c908" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PreCapitalizedTrustSecuritiesRedeemableJuly2028Member_07078f03-5ced-4008-a2b9-ddf39fc00f6a" xlink:href="nrg-20231231.xsd#nrg_PreCapitalizedTrustSecuritiesRedeemableJuly2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cee6cf81-c2ff-4d53-a66a-45752614c908" xlink:to="loc_nrg_PreCapitalizedTrustSecuritiesRedeemableJuly2028Member_07078f03-5ced-4008-a2b9-ddf39fc00f6a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_3bc8f3aa-d170-493d-a000-4848bd30790a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1d5d05bc-8308-48b0-94ea-8c195c724f59" xlink:to="loc_us-gaap_DebtInstrumentAxis_3bc8f3aa-d170-493d-a000-4848bd30790a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_3bc8f3aa-d170-493d-a000-4848bd30790a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_3bc8f3aa-d170-493d-a000-4848bd30790a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_3bc8f3aa-d170-493d-a000-4848bd30790a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8a99b557-66f5-4439-a393-3b4aaca87740" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_3bc8f3aa-d170-493d-a000-4848bd30790a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8a99b557-66f5-4439-a393-3b4aaca87740" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FacilityAgreementMember_5ea6de60-0a70-47a9-b412-465dfca359fb" xlink:href="nrg-20231231.xsd#nrg_FacilityAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8a99b557-66f5-4439-a393-3b4aaca87740" xlink:to="loc_nrg_FacilityAgreementMember_5ea6de60-0a70-47a9-b412-465dfca359fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LCAgreementMember_11a65d4f-0750-473e-8199-d43eec00e29e" xlink:href="nrg-20231231.xsd#nrg_LCAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8a99b557-66f5-4439-a393-3b4aaca87740" xlink:to="loc_nrg_LCAgreementMember_11a65d4f-0750-473e-8199-d43eec00e29e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_228d00de-2777-4557-b8bf-2c66a09ede5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1d5d05bc-8308-48b0-94ea-8c195c724f59" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_228d00de-2777-4557-b8bf-2c66a09ede5a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_228d00de-2777-4557-b8bf-2c66a09ede5a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_228d00de-2777-4557-b8bf-2c66a09ede5a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_228d00de-2777-4557-b8bf-2c66a09ede5a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_be247b71-441b-4f66-93b7-00d8505493e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_228d00de-2777-4557-b8bf-2c66a09ede5a" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_be247b71-441b-4f66-93b7-00d8505493e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SeniorSecuredFirstLienNotesDue2028Member_0d58197b-c7f8-49fd-b681-4c70f8cbb28d" xlink:href="nrg-20231231.xsd#nrg_SeniorSecuredFirstLienNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_be247b71-441b-4f66-93b7-00d8505493e2" xlink:to="loc_nrg_SeniorSecuredFirstLienNotesDue2028Member_0d58197b-c7f8-49fd-b681-4c70f8cbb28d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_098afe2f-c63b-4d38-81af-7de419e24f7c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1d5d05bc-8308-48b0-94ea-8c195c724f59" xlink:to="loc_srt_CounterpartyNameAxis_098afe2f-c63b-4d38-81af-7de419e24f7c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_098afe2f-c63b-4d38-81af-7de419e24f7c_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_098afe2f-c63b-4d38-81af-7de419e24f7c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_098afe2f-c63b-4d38-81af-7de419e24f7c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_82578cd0-af2b-4006-8cb4-c4ada6f255fc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_098afe2f-c63b-4d38-81af-7de419e24f7c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_82578cd0-af2b-4006-8cb4-c4ada6f255fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AlexanderFundingTrustIIMember_7fa03fbd-1b14-4b29-ba47-8925bdd8f2e2" xlink:href="nrg-20231231.xsd#nrg_AlexanderFundingTrustIIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_82578cd0-af2b-4006-8cb4-c4ada6f255fc" xlink:to="loc_nrg_AlexanderFundingTrustIIMember_7fa03fbd-1b14-4b29-ba47-8925bdd8f2e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_252ffc57-0b14-4481-914b-d5c21aa214aa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_1d5d05bc-8308-48b0-94ea-8c195c724f59" xlink:to="loc_us-gaap_CreditFacilityAxis_252ffc57-0b14-4481-914b-d5c21aa214aa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_252ffc57-0b14-4481-914b-d5c21aa214aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_252ffc57-0b14-4481-914b-d5c21aa214aa" xlink:to="loc_us-gaap_CreditFacilityDomain_252ffc57-0b14-4481-914b-d5c21aa214aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_45c3457e-dc86-4d23-981c-fb29a7200dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_252ffc57-0b14-4481-914b-d5c21aa214aa" xlink:to="loc_us-gaap_CreditFacilityDomain_45c3457e-dc86-4d23-981c-fb29a7200dcb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_de0fa3f4-ee2d-40ed-ae81-6a43680daeee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_45c3457e-dc86-4d23-981c-fb29a7200dcb" xlink:to="loc_us-gaap_LetterOfCreditMember_de0fa3f4-ee2d-40ed-ae81-6a43680daeee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_5be0f3ae-c718-4606-914a-acfcb42e68e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:to="loc_us-gaap_DerivativeNotionalAmount_5be0f3ae-c718-4606-914a-acfcb42e68e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_4a9e9cc1-7c35-41dc-aba8-26fb35222197" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_4a9e9cc1-7c35-41dc-aba8-26fb35222197" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_ecce4809-2d30-4be1-921d-e0c238e81510" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_ecce4809-2d30-4be1-921d-e0c238e81510" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TrustFacilityFeeUnexercisedPortionOfIssuanceRightsSemiAnnualPaymentPercentage_19c754cf-d5e4-450a-bc05-45e7f4e0033a" xlink:href="nrg-20231231.xsd#nrg_TrustFacilityFeeUnexercisedPortionOfIssuanceRightsSemiAnnualPaymentPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:to="loc_nrg_TrustFacilityFeeUnexercisedPortionOfIssuanceRightsSemiAnnualPaymentPercentage_19c754cf-d5e4-450a-bc05-45e7f4e0033a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_FailureToPayFacilityFeeCurePeriod_d3ca3c50-575c-4d69-9536-252e771bd500" xlink:href="nrg-20231231.xsd#nrg_FailureToPayFacilityFeeCurePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:to="loc_nrg_FailureToPayFacilityFeeCurePeriod_d3ca3c50-575c-4d69-9536-252e771bd500" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_d3b18fd0-4708-4922-9dd3-2f0ed8b42b8c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ff1ac699-58df-4144-acdf-265332fe9dff" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_d3b18fd0-4708-4922-9dd3-2f0ed8b42b8c" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesVivintSmartHomeAcquiredDebtDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesVivintSmartHomeAcquiredDebtDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesVivintSmartHomeAcquiredDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_5c624eb8-0ad2-447b-af7c-1767200a8751" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_43918846-4ad4-4b78-9eb2-1f767904c037" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5c624eb8-0ad2-447b-af7c-1767200a8751" xlink:to="loc_us-gaap_DebtInstrumentTable_43918846-4ad4-4b78-9eb2-1f767904c037" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_e9705131-d670-4aca-a830-8110bffe58be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_43918846-4ad4-4b78-9eb2-1f767904c037" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_e9705131-d670-4aca-a830-8110bffe58be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_e9705131-d670-4aca-a830-8110bffe58be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_e9705131-d670-4aca-a830-8110bffe58be" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_e9705131-d670-4aca-a830-8110bffe58be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_50a64184-2ab7-45e8-a2bb-650040feb944" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_e9705131-d670-4aca-a830-8110bffe58be" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_50a64184-2ab7-45e8-a2bb-650040feb944" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NonRecourseDebtMember_aa300e03-0d60-46c1-b14c-080aabf0d599" xlink:href="nrg-20231231.xsd#nrg_NonRecourseDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_50a64184-2ab7-45e8-a2bb-650040feb944" xlink:to="loc_nrg_NonRecourseDebtMember_aa300e03-0d60-46c1-b14c-080aabf0d599" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_4917b78f-fe98-40b9-bf2b-0acd676053b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_43918846-4ad4-4b78-9eb2-1f767904c037" xlink:to="loc_us-gaap_DebtInstrumentAxis_4917b78f-fe98-40b9-bf2b-0acd676053b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4917b78f-fe98-40b9-bf2b-0acd676053b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_4917b78f-fe98-40b9-bf2b-0acd676053b7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4917b78f-fe98-40b9-bf2b-0acd676053b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_cfb86db2-eac6-4f9f-9857-0c71c6c1ba1d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_4917b78f-fe98-40b9-bf2b-0acd676053b7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_cfb86db2-eac6-4f9f-9857-0c71c6c1ba1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_Vivint6750SeniorSecuredNotesDue2027Member_9aed911d-e092-44bf-a383-633ccd47cd77" xlink:href="nrg-20231231.xsd#nrg_Vivint6750SeniorSecuredNotesDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cfb86db2-eac6-4f9f-9857-0c71c6c1ba1d" xlink:to="loc_nrg_Vivint6750SeniorSecuredNotesDue2027Member_9aed911d-e092-44bf-a383-633ccd47cd77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_Vivint5750SeniorSecuredNotesDue2029Member_baa5de66-ccfd-47b3-bc1b-a1ea35036b02" xlink:href="nrg-20231231.xsd#nrg_Vivint5750SeniorSecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cfb86db2-eac6-4f9f-9857-0c71c6c1ba1d" xlink:to="loc_nrg_Vivint5750SeniorSecuredNotesDue2029Member_baa5de66-ccfd-47b3-bc1b-a1ea35036b02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintCreditAgreementMember_973df41a-3472-4cc3-abac-7d707ea86b23" xlink:href="nrg-20231231.xsd#nrg_VivintCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cfb86db2-eac6-4f9f-9857-0c71c6c1ba1d" xlink:to="loc_nrg_VivintCreditAgreementMember_973df41a-3472-4cc3-abac-7d707ea86b23" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_ad9e4978-fd0f-4b04-9d6c-cf57931ddff7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_43918846-4ad4-4b78-9eb2-1f767904c037" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_ad9e4978-fd0f-4b04-9d6c-cf57931ddff7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ad9e4978-fd0f-4b04-9d6c-cf57931ddff7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ad9e4978-fd0f-4b04-9d6c-cf57931ddff7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ad9e4978-fd0f-4b04-9d6c-cf57931ddff7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9d727c7b-feb9-46c6-a673-307950af5931" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ad9e4978-fd0f-4b04-9d6c-cf57931ddff7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9d727c7b-feb9-46c6-a673-307950af5931" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintMember_99424acb-a187-441b-92f0-2e28aa6245b8" xlink:href="nrg-20231231.xsd#nrg_VivintMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9d727c7b-feb9-46c6-a673-307950af5931" xlink:to="loc_nrg_VivintMember_99424acb-a187-441b-92f0-2e28aa6245b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_dc09b234-efd7-43ff-acca-383e069413ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_43918846-4ad4-4b78-9eb2-1f767904c037" xlink:to="loc_us-gaap_CreditFacilityAxis_dc09b234-efd7-43ff-acca-383e069413ac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_dc09b234-efd7-43ff-acca-383e069413ac_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_dc09b234-efd7-43ff-acca-383e069413ac" xlink:to="loc_us-gaap_CreditFacilityDomain_dc09b234-efd7-43ff-acca-383e069413ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_b0141c03-9908-4c97-8509-1ad70c42bbb6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_dc09b234-efd7-43ff-acca-383e069413ac" xlink:to="loc_us-gaap_CreditFacilityDomain_b0141c03-9908-4c97-8509-1ad70c42bbb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TermLoanFacilityMember_d630b56c-d159-4365-b160-230093fc0f27" xlink:href="nrg-20231231.xsd#nrg_TermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b0141c03-9908-4c97-8509-1ad70c42bbb6" xlink:to="loc_nrg_TermLoanFacilityMember_d630b56c-d159-4365-b160-230093fc0f27" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_5f7148d4-9e70-4a33-a797-9f8c7519d8c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b0141c03-9908-4c97-8509-1ad70c42bbb6" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_5f7148d4-9e70-4a33-a797-9f8c7519d8c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_3b49b2f4-4903-412a-a7cd-84e133289abe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5c624eb8-0ad2-447b-af7c-1767200a8751" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_3b49b2f4-4903-412a-a7cd-84e133289abe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_3b3fe683-0272-478a-986b-19bcc5330570" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5c624eb8-0ad2-447b-af7c-1767200a8751" xlink:to="loc_us-gaap_LongTermDebt_3b3fe683-0272-478a-986b-19bcc5330570" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_4a4dafe7-04b6-41b0-89b3-8161f6c10c1b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_5c624eb8-0ad2-447b-af7c-1767200a8751" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_4a4dafe7-04b6-41b0-89b3-8161f6c10c1b" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesVivintSeniorNotesRedemptionPeriodDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#LongtermDebtandFinanceLeasesVivintSeniorNotesRedemptionPeriodDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/LongtermDebtandFinanceLeasesVivintSeniorNotesRedemptionPeriodDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_0ba9b832-9616-4702-a317-ca52315471b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_b1a6ea06-dd87-4851-87f5-7e953f8ceaf8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0ba9b832-9616-4702-a317-ca52315471b0" xlink:to="loc_us-gaap_DebtInstrumentTable_b1a6ea06-dd87-4851-87f5-7e953f8ceaf8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_68b5dc1e-2749-49fb-bae4-0bcc7dbfb287" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b1a6ea06-dd87-4851-87f5-7e953f8ceaf8" xlink:to="loc_us-gaap_DebtInstrumentAxis_68b5dc1e-2749-49fb-bae4-0bcc7dbfb287" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_68b5dc1e-2749-49fb-bae4-0bcc7dbfb287_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_68b5dc1e-2749-49fb-bae4-0bcc7dbfb287" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_68b5dc1e-2749-49fb-bae4-0bcc7dbfb287_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_40091c05-5d52-47d7-8343-658f5d171025" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_68b5dc1e-2749-49fb-bae4-0bcc7dbfb287" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_40091c05-5d52-47d7-8343-658f5d171025" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_c9a0c95c-1c09-4aca-a4ed-c88e2797a496" xlink:href="nrg-20231231.xsd#nrg_A3375SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_40091c05-5d52-47d7-8343-658f5d171025" xlink:to="loc_nrg_A3375SeniorUnsecuredNotesDue2029Member_c9a0c95c-1c09-4aca-a4ed-c88e2797a496" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_Vivint6750SeniorSecuredNotesDue2027Member_dfc801ae-2203-4fee-b0dc-1b08aacdc500" xlink:href="nrg-20231231.xsd#nrg_Vivint6750SeniorSecuredNotesDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_40091c05-5d52-47d7-8343-658f5d171025" xlink:to="loc_nrg_Vivint6750SeniorSecuredNotesDue2027Member_dfc801ae-2203-4fee-b0dc-1b08aacdc500" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_b2194526-d90c-4177-a1cb-0ee1234ef394" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b1a6ea06-dd87-4851-87f5-7e953f8ceaf8" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_b2194526-d90c-4177-a1cb-0ee1234ef394" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_b2194526-d90c-4177-a1cb-0ee1234ef394_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_b2194526-d90c-4177-a1cb-0ee1234ef394" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_b2194526-d90c-4177-a1cb-0ee1234ef394_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_b2194526-d90c-4177-a1cb-0ee1234ef394" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152024ToFebruary142025Member_4a50f841-14e2-43aa-9278-bf6893ecf49e" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152024ToFebruary142025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:to="loc_nrg_RedemptionPeriodFebruary152024ToFebruary142025Member_4a50f841-14e2-43aa-9278-bf6893ecf49e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodFebruary152025AndThereafterMember_7e6bc97a-6e18-4af8-8724-be3368229376" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodFebruary152025AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:to="loc_nrg_RedemptionPeriodFebruary152025AndThereafterMember_7e6bc97a-6e18-4af8-8724-be3368229376" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodPriorToJuly152024Member_c8130c2b-f8a4-4eb3-97d9-c707ea5d1f71" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodPriorToJuly152024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:to="loc_nrg_RedemptionPeriodPriorToJuly152024Member_c8130c2b-f8a4-4eb3-97d9-c707ea5d1f71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodJuly152024ToJuly142025Member_11971911-314f-4f56-8262-4305fe2f9f46" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodJuly152024ToJuly142025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:to="loc_nrg_RedemptionPeriodJuly152024ToJuly142025Member_11971911-314f-4f56-8262-4305fe2f9f46" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodJuly152025ToJuly142026Member_9a519ba3-c8a2-4ce1-acd5-7018be8139f0" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodJuly152025ToJuly142026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:to="loc_nrg_RedemptionPeriodJuly152025ToJuly142026Member_9a519ba3-c8a2-4ce1-acd5-7018be8139f0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RedemptionPeriodJuly152026AndThereafterMember_6fc1b97d-4e91-4ae4-bc4a-640e42cb87f6" xlink:href="nrg-20231231.xsd#nrg_RedemptionPeriodJuly152026AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3568b2fc-2513-4a81-9c68-36993f1b3695" xlink:to="loc_nrg_RedemptionPeriodJuly152026AndThereafterMember_6fc1b97d-4e91-4ae4-bc4a-640e42cb87f6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_7026a333-ee04-4556-9adb-e283c5debe3b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b1a6ea06-dd87-4851-87f5-7e953f8ceaf8" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_7026a333-ee04-4556-9adb-e283c5debe3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7026a333-ee04-4556-9adb-e283c5debe3b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7026a333-ee04-4556-9adb-e283c5debe3b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7026a333-ee04-4556-9adb-e283c5debe3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_25a661ab-5583-44a9-a513-604fc5630f9e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7026a333-ee04-4556-9adb-e283c5debe3b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_25a661ab-5583-44a9-a513-604fc5630f9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_628d3652-f2a1-45dc-9b98-c809e8053fa8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_25a661ab-5583-44a9-a513-604fc5630f9e" xlink:to="loc_us-gaap_SeniorNotesMember_628d3652-f2a1-45dc-9b98-c809e8053fa8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_d67dbb0e-81e4-4e91-adb8-58e67f85f146" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_b1a6ea06-dd87-4851-87f5-7e953f8ceaf8" xlink:to="loc_us-gaap_VariableRateAxis_d67dbb0e-81e4-4e91-adb8-58e67f85f146" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_d67dbb0e-81e4-4e91-adb8-58e67f85f146_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_d67dbb0e-81e4-4e91-adb8-58e67f85f146" xlink:to="loc_us-gaap_VariableRateDomain_d67dbb0e-81e4-4e91-adb8-58e67f85f146_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_eb4a95cb-c365-4375-bec3-1acae1cfe1ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_d67dbb0e-81e4-4e91-adb8-58e67f85f146" xlink:to="loc_us-gaap_VariableRateDomain_eb4a95cb-c365-4375-bec3-1acae1cfe1ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TreasuryRateMember_efb77ad3-dd14-4916-9da8-0bcb831f8878" xlink:href="nrg-20231231.xsd#nrg_TreasuryRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_eb4a95cb-c365-4375-bec3-1acae1cfe1ee" xlink:to="loc_nrg_TreasuryRateMember_efb77ad3-dd14-4916-9da8-0bcb831f8878" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_ad819cbd-f89b-4391-bb00-4f2e5510b13a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0ba9b832-9616-4702-a317-ca52315471b0" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_ad819cbd-f89b-4391-bb00-4f2e5510b13a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PremiumPercentageOfPrincipalOfSeniorNotesDiscountFactor_55943932-2c84-40d2-b7bb-bce27d238212" xlink:href="nrg-20231231.xsd#nrg_PremiumPercentageOfPrincipalOfSeniorNotesDiscountFactor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0ba9b832-9616-4702-a317-ca52315471b0" xlink:to="loc_nrg_PremiumPercentageOfPrincipalOfSeniorNotesDiscountFactor_55943932-2c84-40d2-b7bb-bce27d238212" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_e32ad8c6-ee2c-4030-8cb3-cc7f0df58b56" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0ba9b832-9616-4702-a317-ca52315471b0" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_e32ad8c6-ee2c-4030-8cb3-cc7f0df58b56" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/AssetRetirementObligationsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#AssetRetirementObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/AssetRetirementObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetRetirementObligationsLineItems_6d4041f9-0c45-42b5-9edd-26a138942477" xlink:href="nrg-20231231.xsd#nrg_AssetRetirementObligationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetRetirementObligationTable_544da0cc-8754-430b-9482-0f5b7c684205" xlink:href="nrg-20231231.xsd#nrg_AssetRetirementObligationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_nrg_AssetRetirementObligationsLineItems_6d4041f9-0c45-42b5-9edd-26a138942477" xlink:to="loc_nrg_AssetRetirementObligationTable_544da0cc-8754-430b-9482-0f5b7c684205" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetRetirementObligationsAxis_0e9e31a4-8cb5-4999-811e-3d31271ec003" xlink:href="nrg-20231231.xsd#nrg_AssetRetirementObligationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_AssetRetirementObligationTable_544da0cc-8754-430b-9482-0f5b7c684205" xlink:to="loc_nrg_AssetRetirementObligationsAxis_0e9e31a4-8cb5-4999-811e-3d31271ec003" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetRetirementObligationsDomain_0e9e31a4-8cb5-4999-811e-3d31271ec003_default" xlink:href="nrg-20231231.xsd#nrg_AssetRetirementObligationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nrg_AssetRetirementObligationsAxis_0e9e31a4-8cb5-4999-811e-3d31271ec003" xlink:to="loc_nrg_AssetRetirementObligationsDomain_0e9e31a4-8cb5-4999-811e-3d31271ec003_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetRetirementObligationsDomain_3573e659-5a86-4068-929e-f45deb78ef93" xlink:href="nrg-20231231.xsd#nrg_AssetRetirementObligationsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nrg_AssetRetirementObligationsAxis_0e9e31a4-8cb5-4999-811e-3d31271ec003" xlink:to="loc_nrg_AssetRetirementObligationsDomain_3573e659-5a86-4068-929e-f45deb78ef93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NuclearDecommissionMember_7a9db65c-4682-4479-ad63-dc95c03dddec" xlink:href="nrg-20231231.xsd#nrg_NuclearDecommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AssetRetirementObligationsDomain_3573e659-5a86-4068-929e-f45deb78ef93" xlink:to="loc_nrg_NuclearDecommissionMember_7a9db65c-4682-4479-ad63-dc95c03dddec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_OtherAssetRetirementObligationsMember_9d682b09-41f5-4ec5-ab50-c10c23af54bc" xlink:href="nrg-20231231.xsd#nrg_OtherAssetRetirementObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AssetRetirementObligationsDomain_3573e659-5a86-4068-929e-f45deb78ef93" xlink:to="loc_nrg_OtherAssetRetirementObligationsMember_9d682b09-41f5-4ec5-ab50-c10c23af54bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c7c2d315-df06-4683-b266-254f768253e2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_AssetRetirementObligationTable_544da0cc-8754-430b-9482-0f5b7c684205" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c7c2d315-df06-4683-b266-254f768253e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_c7c2d315-df06-4683-b266-254f768253e2_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c7c2d315-df06-4683-b266-254f768253e2" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_c7c2d315-df06-4683-b266-254f768253e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_af12c917-a4aa-4b98-8c71-a66326ce65bc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c7c2d315-df06-4683-b266-254f768253e2" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_af12c917-a4aa-4b98-8c71-a66326ce65bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_f69b81f1-5b5a-4ebe-b98e-983c9c037d90" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_af12c917-a4aa-4b98-8c71-a66326ce65bc" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_f69b81f1-5b5a-4ebe-b98e-983c9c037d90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_49aaea7a-b2b9-4eb7-a70b-7a0eace5f54c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_nrg_AssetRetirementObligationTable_544da0cc-8754-430b-9482-0f5b7c684205" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_49aaea7a-b2b9-4eb7-a70b-7a0eace5f54c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_49aaea7a-b2b9-4eb7-a70b-7a0eace5f54c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_49aaea7a-b2b9-4eb7-a70b-7a0eace5f54c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_49aaea7a-b2b9-4eb7-a70b-7a0eace5f54c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_da6009db-c9a2-465b-a792-c72e3a9b0b8e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_49aaea7a-b2b9-4eb7-a70b-7a0eace5f54c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_da6009db-c9a2-465b-a792-c72e3a9b0b8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_f8ddb8d8-96b5-4e7b-8f09-77f5840680af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_da6009db-c9a2-465b-a792-c72e3a9b0b8e" xlink:to="loc_us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember_f8ddb8d8-96b5-4e7b-8f09-77f5840680af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_eb269348-4497-42c1-a372-846c5b35e0b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AssetRetirementObligationsLineItems_6d4041f9-0c45-42b5-9edd-26a138942477" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_eb269348-4497-42c1-a372-846c5b35e0b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AssetRetirementObligationsLineItems_6d4041f9-0c45-42b5-9edd-26a138942477" xlink:to="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligation_c6e4e163-ed7b-4d5b-acca-1dfb36ca96fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetRetirementObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:to="loc_us-gaap_AssetRetirementObligation_c6e4e163-ed7b-4d5b-acca-1dfb36ca96fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationRevisionOfEstimate_843d0753-ef7e-4aa0-a151-3ae37aa7a31a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetRetirementObligationRevisionOfEstimate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:to="loc_us-gaap_AssetRetirementObligationRevisionOfEstimate_843d0753-ef7e-4aa0-a151-3ae37aa7a31a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsIncurredAssetRetirementObligationIncurred_46eae9f4-f1ac-4079-882d-6e554e69bfb7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsIncurredAssetRetirementObligationIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:to="loc_us-gaap_CostsIncurredAssetRetirementObligationIncurred_46eae9f4-f1ac-4079-882d-6e554e69bfb7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationLiabilitiesIncurred_f3802744-78e5-4b45-8b39-534c02dd9160" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetRetirementObligationLiabilitiesIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:to="loc_us-gaap_AssetRetirementObligationLiabilitiesIncurred_f3802744-78e5-4b45-8b39-534c02dd9160" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationAccretionExpense_88103f1d-b743-4bf1-b142-3410ff20db23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetRetirementObligationAccretionExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:to="loc_us-gaap_AssetRetirementObligationAccretionExpense_88103f1d-b743-4bf1-b142-3410ff20db23" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetRetirementObligationsOther_6194d361-bbb9-4487-8182-575dd3c26dfe" xlink:href="nrg-20231231.xsd#nrg_AssetRetirementObligationsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward_4476ce63-6ec5-4d57-ac6d-a7a21d9ec1f1" xlink:to="loc_nrg_AssetRetirementObligationsOther_6194d361-bbb9-4487-8182-575dd3c26dfe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligation_c2c80de5-a74d-404c-9b4b-704741180713" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetRetirementObligation"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#BenefitPlansandOtherPostretirementBenefitsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e9e09b93-642f-4808-9327-b3126ca007ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0fb91004-031c-4d02-a610-5a821f0414c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e9e09b93-642f-4808-9327-b3126ca007ba" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0fb91004-031c-4d02-a610-5a821f0414c1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_c5b7b1d7-2dee-412b-b291-c4713463ca02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0fb91004-031c-4d02-a610-5a821f0414c1" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_c5b7b1d7-2dee-412b-b291-c4713463ca02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_c5b7b1d7-2dee-412b-b291-c4713463ca02_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_c5b7b1d7-2dee-412b-b291-c4713463ca02" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_c5b7b1d7-2dee-412b-b291-c4713463ca02_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_fb9d2a13-78a5-4ca7-8754-f6ee163cf94c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_c5b7b1d7-2dee-412b-b291-c4713463ca02" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_fb9d2a13-78a5-4ca7-8754-f6ee163cf94c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_f21304f8-66c5-41d8-84c9-1ef8411c9057" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_fb9d2a13-78a5-4ca7-8754-f6ee163cf94c" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_f21304f8-66c5-41d8-84c9-1ef8411c9057" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_40ca2057-14f0-45e3-8151-2c2f9e063d93" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0fb91004-031c-4d02-a610-5a821f0414c1" xlink:to="loc_dei_LegalEntityAxis_40ca2057-14f0-45e3-8151-2c2f9e063d93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_40ca2057-14f0-45e3-8151-2c2f9e063d93_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_40ca2057-14f0-45e3-8151-2c2f9e063d93" xlink:to="loc_dei_EntityDomain_40ca2057-14f0-45e3-8151-2c2f9e063d93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_77f03174-bc39-48c5-80e5-86c47e4c8794" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_40ca2057-14f0-45e3-8151-2c2f9e063d93" xlink:to="loc_dei_EntityDomain_77f03174-bc39-48c5-80e5-86c47e4c8794" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GenOnMember_f0ed713f-9347-4b50-807f-bc38eec33828" xlink:href="nrg-20231231.xsd#nrg_GenOnMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_77f03174-bc39-48c5-80e5-86c47e4c8794" xlink:to="loc_nrg_GenOnMember_f0ed713f-9347-4b50-807f-bc38eec33828" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6f43a436-f818-4711-acc8-6b5a94fd2053" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0fb91004-031c-4d02-a610-5a821f0414c1" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6f43a436-f818-4711-acc8-6b5a94fd2053" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_6f43a436-f818-4711-acc8-6b5a94fd2053_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6f43a436-f818-4711-acc8-6b5a94fd2053" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_6f43a436-f818-4711-acc8-6b5a94fd2053_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_3b77bb2c-f271-4877-884c-7093d0333088" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_6f43a436-f818-4711-acc8-6b5a94fd2053" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_3b77bb2c-f271-4877-884c-7093d0333088" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_24700cf7-7e8a-4c93-b8b2-89cd8e913136" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_3b77bb2c-f271-4877-884c-7093d0333088" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_24700cf7-7e8a-4c93-b8b2-89cd8e913136" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfDefinedBenefitPlans_9b1c8d37-8372-4206-9c20-21ef15a1f719" xlink:href="nrg-20231231.xsd#nrg_NumberOfDefinedBenefitPlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e9e09b93-642f-4808-9327-b3126ca007ba" xlink:to="loc_nrg_NumberOfDefinedBenefitPlans_9b1c8d37-8372-4206-9c20-21ef15a1f719" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear_4c7eb033-f334-41e0-abbf-0fd259692b02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e9e09b93-642f-4808-9327-b3126ca007ba" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear_4c7eb033-f334-41e0-abbf-0fd259692b02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_7a6940be-4f89-4dfc-ab79-a26a2fd2413c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e9e09b93-642f-4808-9327-b3126ca007ba" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_7a6940be-4f89-4dfc-ab79-a26a2fd2413c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_f5573f10-5895-4ab2-8468-58b79ab88aa1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e9e09b93-642f-4808-9327-b3126ca007ba" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_f5573f10-5895-4ab2-8468-58b79ab88aa1" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsNetBenefitCostsandFundedStatusDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#BenefitPlansandOtherPostretirementBenefitsNetBenefitCostsandFundedStatusDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsNetBenefitCostsandFundedStatusDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3cf1f24e-a0a5-47c1-8ba8-f54a10097ade" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_3d10248d-21e1-4bb9-8545-4a1f4b0ed748" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3cf1f24e-a0a5-47c1-8ba8-f54a10097ade" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_3d10248d-21e1-4bb9-8545-4a1f4b0ed748" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_1d880a07-268b-4569-9414-353b50a72b97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_3d10248d-21e1-4bb9-8545-4a1f4b0ed748" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_1d880a07-268b-4569-9414-353b50a72b97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_1d880a07-268b-4569-9414-353b50a72b97_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_1d880a07-268b-4569-9414-353b50a72b97" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_1d880a07-268b-4569-9414-353b50a72b97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_00e2738c-b6d6-41ab-ab72-208c3e450053" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_1d880a07-268b-4569-9414-353b50a72b97" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_00e2738c-b6d6-41ab-ab72-208c3e450053" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_c32eae27-8fd1-4a0d-ac93-1e553d886e39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_00e2738c-b6d6-41ab-ab72-208c3e450053" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_c32eae27-8fd1-4a0d-ac93-1e553d886e39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_97676301-602b-4db5-98ba-98b281169d3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_00e2738c-b6d6-41ab-ab72-208c3e450053" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_97676301-602b-4db5-98ba-98b281169d3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3cf1f24e-a0a5-47c1-8ba8-f54a10097ade" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_bd62eb24-6c6e-4dcc-be90-a63972144847" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_bd62eb24-6c6e-4dcc-be90-a63972144847" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_24b8e0f2-69fb-4c39-b96b-d381053e5f6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_24b8e0f2-69fb-4c39-b96b-d381053e5f6a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_22c41ab1-2073-4294-98e4-cad1b41a031f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_22c41ab1-2073-4294-98e4-cad1b41a031f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_af157665-e60e-4d67-a550-a3b8245f0f1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_af157665-e60e-4d67-a550-a3b8245f0f1e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_ca45974d-f095-4e9b-8c7b-725924b5a468" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_ca45974d-f095-4e9b-8c7b-725924b5a468" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments_43569e63-682b-4221-af3b-f496d1157693" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToCurtailments_43569e63-682b-4221-af3b-f496d1157693" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_228c704d-e360-4ba9-92f4-ebb59aec6e0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_de8efc5a-4895-477e-90c1-97c786d5a405" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_228c704d-e360-4ba9-92f4-ebb59aec6e0b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3cf1f24e-a0a5-47c1-8ba8-f54a10097ade" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_8e2a0477-421e-4596-b481-c3fea7b88533" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_8e2a0477-421e-4596-b481-c3fea7b88533" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_f6a7ee66-7336-4070-bbaa-c602ea0a25d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_0c95ab58-db00-4455-a471-e9d60476991c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_59edc456-1246-456e-9c5c-09aa5baceff7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_59edc456-1246-456e-9c5c-09aa5baceff7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_feac5100-4037-446d-9395-381bf9fa29e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_feac5100-4037-446d-9395-381bf9fa29e6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligationIncreaseDecreaseForSettlementAndCurtailment_59f58298-6092-45b8-97a1-cb3b52ca7031" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAccumulatedBenefitObligationIncreaseDecreaseForSettlementAndCurtailment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligationIncreaseDecreaseForSettlementAndCurtailment_59f58298-6092-45b8-97a1-cb3b52ca7031" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_e5d19e40-513b-4bb3-9130-3fd022fd3806" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_e5d19e40-513b-4bb3-9130-3fd022fd3806" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_c41ae228-cd8b-432c-8e68-d4e5d2b2295d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_c4bc60fb-2896-47e8-88e3-1de1216a1225" xlink:to="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_c41ae228-cd8b-432c-8e68-d4e5d2b2295d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_c6f3fb64-4f08-4352-b6fe-14ebaa4ae422" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3cf1f24e-a0a5-47c1-8ba8-f54a10097ade" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_e4881eab-8a85-475b-9363-a5470abcb30f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_e4881eab-8a85-475b-9363-a5470abcb30f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_562bf3a7-7019-4ac8-9f8a-3084a8526c67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:to="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_562bf3a7-7019-4ac8-9f8a-3084a8526c67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant_12033d5c-a050-46f9-ad71-89e9c628c129" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant_12033d5c-a050-46f9-ad71-89e9c628c129" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_3e9affef-0967-42d8-b648-ebd0a3bf1458" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_3e9affef-0967-42d8-b648-ebd0a3bf1458" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_374f3a88-3bf7-4673-8663-5179772cbc81" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_374f3a88-3bf7-4673-8663-5179772cbc81" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_c7a18c6e-d543-4fb2-b4c3-68733478a7cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_5468640b-529d-44a5-b804-5e423c96858f" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_c7a18c6e-d543-4fb2-b4c3-68733478a7cb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_7fb6e4be-7af8-4de3-9c97-3db35bffef56" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_fc7f3328-6672-44c8-aa85-28cc3ab234a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3cf1f24e-a0a5-47c1-8ba8-f54a10097ade" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_fc7f3328-6672-44c8-aa85-28cc3ab234a4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsAmountsRecognizedintheBalanceSheetsandOCIDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#BenefitPlansandOtherPostretirementBenefitsAmountsRecognizedintheBalanceSheetsandOCIDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsAmountsRecognizedintheBalanceSheetsandOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_34693c9c-1fdc-41a4-b8f8-8604921f2b44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_9eadac1d-7c9e-4ec1-b52d-bd27bdcb3116" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_34693c9c-1fdc-41a4-b8f8-8604921f2b44" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_9eadac1d-7c9e-4ec1-b52d-bd27bdcb3116" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_35fb5266-c053-481d-a903-88e39cb311d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_9eadac1d-7c9e-4ec1-b52d-bd27bdcb3116" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_35fb5266-c053-481d-a903-88e39cb311d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_35fb5266-c053-481d-a903-88e39cb311d4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_35fb5266-c053-481d-a903-88e39cb311d4" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_35fb5266-c053-481d-a903-88e39cb311d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_6072dddf-084d-4d3d-9a76-6ca640178a8b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_35fb5266-c053-481d-a903-88e39cb311d4" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_6072dddf-084d-4d3d-9a76-6ca640178a8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_7e67712d-95e6-479e-b390-02fdef36ba6d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_6072dddf-084d-4d3d-9a76-6ca640178a8b" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_7e67712d-95e6-479e-b390-02fdef36ba6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_f8c19b7b-1c24-42b8-b482-07204d61dba5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_6072dddf-084d-4d3d-9a76-6ca640178a8b" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_f8c19b7b-1c24-42b8-b482-07204d61dba5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_7ced96e8-48cd-4008-b319-56cde57def91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_34693c9c-1fdc-41a4-b8f8-8604921f2b44" xlink:to="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_7ced96e8-48cd-4008-b319-56cde57def91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_32769e50-aeac-4de2-b4b6-1f0e43391ac6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_7ced96e8-48cd-4008-b319-56cde57def91" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_32769e50-aeac-4de2-b4b6-1f0e43391ac6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_3da42ede-6dbe-45e4-89f5-227f6adc38ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_7ced96e8-48cd-4008-b319-56cde57def91" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_3da42ede-6dbe-45e4-89f5-227f6adc38ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_8435e96e-7dd3-4a57-9639-65f6586da9c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_34693c9c-1fdc-41a4-b8f8-8604921f2b44" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_8435e96e-7dd3-4a57-9639-65f6586da9c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_1422ba82-7430-48e9-9a0f-4a1fd0398dbb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_8435e96e-7dd3-4a57-9639-65f6586da9c4" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_1422ba82-7430-48e9-9a0f-4a1fd0398dbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax_a41132f0-cc75-4547-930b-7de49ce00c43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_8435e96e-7dd3-4a57-9639-65f6586da9c4" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax_a41132f0-cc75-4547-930b-7de49ce00c43" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_ecc0ab78-74fa-4695-ae1a-f40d23b79ee1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_8435e96e-7dd3-4a57-9639-65f6586da9c4" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_ecc0ab78-74fa-4695-ae1a-f40d23b79ee1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_34693c9c-1fdc-41a4-b8f8-8604921f2b44" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax_d2616072-6b9f-4d02-a02a-6beba2b6d3c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax_d2616072-6b9f-4d02-a02a-6beba2b6d3c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax_44f4ddba-071c-4e30-92bb-7a2b6cb9d0fb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax_44f4ddba-071c-4e30-92bb-7a2b6cb9d0fb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax_8df4de21-c83c-4967-92e2-16a207c24e36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax_8df4de21-c83c-4967-92e2-16a207c24e36" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax_75c44c17-5558-4032-9c32-620e494fe9dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossFinalizationOfPensionAndNonPensionPostretirementPlanValuationBeforeTax_75c44c17-5558-4032-9c32-620e494fe9dd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_34a4cd88-d217-4f2d-bd2f-029b14740bce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_34a4cd88-d217-4f2d-bd2f-029b14740bce" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_3948c970-9088-4500-99ec-eae13e6c0980" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_3948c970-9088-4500-99ec-eae13e6c0980" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax_f9c80cb9-cf7f-4b08-9063-fc61ff01ba46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentBeforeTaxPeriodIncreaseDecreaseAbstract_473944fd-309b-4566-b3b0-036f71636dac" xlink:to="loc_us-gaap_AmountRecognizedInNetPeriodicBenefitCostAndOtherComprehensiveIncomeLossBeforeTax_f9c80cb9-cf7f-4b08-9063-fc61ff01ba46" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SignificantComponentsOfDefinedBenefitPensionPlanAbstract_0cd8c232-44de-4b4f-ad63-4f432efe796e" xlink:href="nrg-20231231.xsd#nrg_SignificantComponentsOfDefinedBenefitPensionPlanAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_34693c9c-1fdc-41a4-b8f8-8604921f2b44" xlink:to="loc_nrg_SignificantComponentsOfDefinedBenefitPensionPlanAbstract_0cd8c232-44de-4b4f-ad63-4f432efe796e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_f20394dd-e20d-409c-920a-2bafaf0c9caa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SignificantComponentsOfDefinedBenefitPensionPlanAbstract_0cd8c232-44de-4b4f-ad63-4f432efe796e" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_f20394dd-e20d-409c-920a-2bafaf0c9caa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_3aac4530-f7da-467b-bc09-f3058c60f23f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SignificantComponentsOfDefinedBenefitPensionPlanAbstract_0cd8c232-44de-4b4f-ad63-4f432efe796e" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_3aac4530-f7da-467b-bc09-f3058c60f23f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_b67659fe-cbb9-4f74-bea5-9d6e18070495" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SignificantComponentsOfDefinedBenefitPensionPlanAbstract_0cd8c232-44de-4b4f-ad63-4f432efe796e" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_b67659fe-cbb9-4f74-bea5-9d6e18070495" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsFairValuesofPensionAssetsbyAssetCategoryandLevelWithintheFairValueHierarchyDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#BenefitPlansandOtherPostretirementBenefitsFairValuesofPensionAssetsbyAssetCategoryandLevelWithintheFairValueHierarchyDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsFairValuesofPensionAssetsbyAssetCategoryandLevelWithintheFairValueHierarchyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b342c18c-de8d-4f30-a335-21a2eadd0481" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b342c18c-de8d-4f30-a335-21a2eadd0481" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_ce50cffb-8b55-441f-8c35-3e7f4372ffb7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b342c18c-de8d-4f30-a335-21a2eadd0481" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_ce50cffb-8b55-441f-8c35-3e7f4372ffb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_ce50cffb-8b55-441f-8c35-3e7f4372ffb7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ce50cffb-8b55-441f-8c35-3e7f4372ffb7" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_ce50cffb-8b55-441f-8c35-3e7f4372ffb7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_7978591c-e99c-4e89-b2b1-870ba678091e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ce50cffb-8b55-441f-8c35-3e7f4372ffb7" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_7978591c-e99c-4e89-b2b1-870ba678091e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_ce2470aa-788f-46eb-953f-902e23873115" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_7978591c-e99c-4e89-b2b1-870ba678091e" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_ce2470aa-788f-46eb-953f-902e23873115" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_757de2d2-3dfe-49e2-8c5e-9376b848c4bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_7978591c-e99c-4e89-b2b1-870ba678091e" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_757de2d2-3dfe-49e2-8c5e-9376b848c4bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_36424531-7457-4e17-968c-2cb9c7e2a937" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b342c18c-de8d-4f30-a335-21a2eadd0481" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_36424531-7457-4e17-968c-2cb9c7e2a937" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_36424531-7457-4e17-968c-2cb9c7e2a937_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_36424531-7457-4e17-968c-2cb9c7e2a937" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_36424531-7457-4e17-968c-2cb9c7e2a937_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9deb1c9a-cfca-4623-84c3-698308fb2647" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_36424531-7457-4e17-968c-2cb9c7e2a937" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9deb1c9a-cfca-4623-84c3-698308fb2647" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_de3da1c8-9fa5-4d01-9845-bd542ea69374" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9deb1c9a-cfca-4623-84c3-698308fb2647" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_de3da1c8-9fa5-4d01-9845-bd542ea69374" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_d6a9486b-f38b-4b7c-8087-f08ba59384ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9deb1c9a-cfca-4623-84c3-698308fb2647" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_d6a9486b-f38b-4b7c-8087-f08ba59384ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel12And3Member_c173abb1-48d2-466d-8af4-e5d83210c8b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel12And3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9deb1c9a-cfca-4623-84c3-698308fb2647" xlink:to="loc_us-gaap_FairValueInputsLevel12And3Member_c173abb1-48d2-466d-8af4-e5d83210c8b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_65855e28-ba06-4441-803f-dc63f89ad452" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9deb1c9a-cfca-4623-84c3-698308fb2647" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_65855e28-ba06-4441-803f-dc63f89ad452" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_de369cb1-c560-4891-b8d7-8de4f5fd28c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b342c18c-de8d-4f30-a335-21a2eadd0481" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_de369cb1-c560-4891-b8d7-8de4f5fd28c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_de369cb1-c560-4891-b8d7-8de4f5fd28c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_de369cb1-c560-4891-b8d7-8de4f5fd28c1" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_de369cb1-c560-4891-b8d7-8de4f5fd28c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_de369cb1-c560-4891-b8d7-8de4f5fd28c1" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonTrustInvestmentUsEquitySecuritiesMember_928cdbf0-b71f-4d83-bba1-114a444f90d5" xlink:href="nrg-20231231.xsd#nrg_CommonTrustInvestmentUsEquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:to="loc_nrg_CommonTrustInvestmentUsEquitySecuritiesMember_928cdbf0-b71f-4d83-bba1-114a444f90d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonTrustInvestmentNonUsEquitySecuritiesMember_cf85e076-610c-45c4-a504-804bd3d913d7" xlink:href="nrg-20231231.xsd#nrg_CommonTrustInvestmentNonUsEquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:to="loc_nrg_CommonTrustInvestmentNonUsEquitySecuritiesMember_cf85e076-610c-45c4-a504-804bd3d913d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmergingMarketEquitiesMember_c2e8416c-f8d7-4c33-862d-4e44757b56ba" xlink:href="nrg-20231231.xsd#nrg_EmergingMarketEquitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:to="loc_nrg_EmergingMarketEquitiesMember_c2e8416c-f8d7-4c33-862d-4e44757b56ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonTrustInvestmentFixedIncomeSecuritiesMember_9414b9d2-9658-4cf3-89c3-0b9c9d743486" xlink:href="nrg-20231231.xsd#nrg_CommonTrustInvestmentFixedIncomeSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:to="loc_nrg_CommonTrustInvestmentFixedIncomeSecuritiesMember_9414b9d2-9658-4cf3-89c3-0b9c9d743486" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestmentsMember_d2c0eb94-60e5-4649-96be-219b029c4d51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:to="loc_us-gaap_ShortTermInvestmentsMember_d2c0eb94-60e5-4649-96be-219b029c4d51" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnershipMember_2296b179-392a-4591-ab0c-c68099d1795b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PartnershipMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_8630f5ff-a3c7-46bf-94c0-605db023d9f4" xlink:to="loc_us-gaap_PartnershipMember_2296b179-392a-4591-ab0c-c68099d1795b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccountTypeAxis_0512cc2c-c8ef-4c70-ae04-32585505a5a4" xlink:href="nrg-20231231.xsd#nrg_AccountTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b342c18c-de8d-4f30-a335-21a2eadd0481" xlink:to="loc_nrg_AccountTypeAxis_0512cc2c-c8ef-4c70-ae04-32585505a5a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccountTypeDomain_0512cc2c-c8ef-4c70-ae04-32585505a5a4_default" xlink:href="nrg-20231231.xsd#nrg_AccountTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nrg_AccountTypeAxis_0512cc2c-c8ef-4c70-ae04-32585505a5a4" xlink:to="loc_nrg_AccountTypeDomain_0512cc2c-c8ef-4c70-ae04-32585505a5a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccountTypeDomain_10f32bf0-8fe5-4a46-b8e4-4eb9d11f06cb" xlink:href="nrg-20231231.xsd#nrg_AccountTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nrg_AccountTypeAxis_0512cc2c-c8ef-4c70-ae04-32585505a5a4" xlink:to="loc_nrg_AccountTypeDomain_10f32bf0-8fe5-4a46-b8e4-4eb9d11f06cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NetPeriodBenefitCostCreditMember_dd576f86-70f6-4a31-8320-31a247c48e44" xlink:href="nrg-20231231.xsd#nrg_NetPeriodBenefitCostCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AccountTypeDomain_10f32bf0-8fe5-4a46-b8e4-4eb9d11f06cb" xlink:to="loc_nrg_NetPeriodBenefitCostCreditMember_dd576f86-70f6-4a31-8320-31a247c48e44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_19dc5e78-ac32-472b-82ee-13bee6d25883" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_b342c18c-de8d-4f30-a335-21a2eadd0481" xlink:to="loc_srt_RangeAxis_19dc5e78-ac32-472b-82ee-13bee6d25883" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_19dc5e78-ac32-472b-82ee-13bee6d25883_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_19dc5e78-ac32-472b-82ee-13bee6d25883" xlink:to="loc_srt_RangeMember_19dc5e78-ac32-472b-82ee-13bee6d25883_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7ffdb1c8-39f5-4cf4-b75f-d85b1c77ac84" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_19dc5e78-ac32-472b-82ee-13bee6d25883" xlink:to="loc_srt_RangeMember_7ffdb1c8-39f5-4cf4-b75f-d85b1c77ac84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_04bd4ac6-0f3a-4f3b-a810-02dd77417b4a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7ffdb1c8-39f5-4cf4-b75f-d85b1c77ac84" xlink:to="loc_srt_MinimumMember_04bd4ac6-0f3a-4f3b-a810-02dd77417b4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_d440ed1c-b30a-4478-a8f2-f4b72c4b22d0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7ffdb1c8-39f5-4cf4-b75f-d85b1c77ac84" xlink:to="loc_srt_WeightedAverageMember_d440ed1c-b30a-4478-a8f2-f4b72c4b22d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d52c6bf6-7b05-47a8-b6f4-ca42aa49ba03" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7ffdb1c8-39f5-4cf4-b75f-d85b1c77ac84" xlink:to="loc_srt_MaximumMember_d52c6bf6-7b05-47a8-b6f4-ca42aa49ba03" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_2c97f201-d931-433a-9a7d-a84bff1f5c86" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_2c97f201-d931-433a-9a7d-a84bff1f5c86" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_d9cecb89-98bf-410d-9357-0b8970ce5d84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_d9cecb89-98bf-410d-9357-0b8970ce5d84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_88e6fcd0-c0b7-4dc7-85ed-8805541f7add" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_d9cecb89-98bf-410d-9357-0b8970ce5d84" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_88e6fcd0-c0b7-4dc7-85ed-8805541f7add" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate_5a8bffa4-530b-42e9-a056-bce7e08bf711" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_d9cecb89-98bf-410d-9357-0b8970ce5d84" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate_5a8bffa4-530b-42e9-a056-bce7e08bf711" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_da169781-fae5-481e-9ef2-891cc92fcd47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_d9cecb89-98bf-410d-9357-0b8970ce5d84" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease_da169781-fae5-481e-9ef2-891cc92fcd47" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear_2fb3efb5-79df-4f42-b623-90b87c5c967e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear_2fb3efb5-79df-4f42-b623-90b87c5c967e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1_444516b1-ddd3-4210-9168-fb2acff828e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1_444516b1-ddd3-4210-9168-fb2acff828e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanYearHealthCareCostTrendRateReachesUltimateTrendRate_007a9436-09ba-4df4-b354-6630a99dd753" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanYearHealthCareCostTrendRateReachesUltimateTrendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_DefinedBenefitPlanYearHealthCareCostTrendRateReachesUltimateTrendRate_007a9436-09ba-4df4-b354-6630a99dd753" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5a1efc59-5353-4758-99fd-33d34735c9ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5a1efc59-5353-4758-99fd-33d34735c9ea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_0880826d-82cf-46f4-b4b4-2f785edb2447" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5a1efc59-5353-4758-99fd-33d34735c9ea" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_0880826d-82cf-46f4-b4b4-2f785edb2447" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostWeightedAverageInterestCreditingRate_bfd43534-777f-45f1-96ca-0ae0fca27bd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostWeightedAverageInterestCreditingRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5a1efc59-5353-4758-99fd-33d34735c9ea" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostWeightedAverageInterestCreditingRate_bfd43534-777f-45f1-96ca-0ae0fca27bd9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_fa81340b-9347-42f8-b750-e084059fba11" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5a1efc59-5353-4758-99fd-33d34735c9ea" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_fa81340b-9347-42f8-b750-e084059fba11" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_2eb8eb0d-f724-4d22-af58-27da606794a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5a1efc59-5353-4758-99fd-33d34735c9ea" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease_2eb8eb0d-f724-4d22-af58-27da606794a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear_af856814-c51e-459e-a0ec-1166409bc0dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanYearHealthCareCostTrendRateReachesUltimateTrendRate_c0893b4b-21ad-442e-af83-8b0d04036ef7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanYearHealthCareCostTrendRateReachesUltimateTrendRate"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AonHewittAboveMedianYieldCurveDiscountRateYears_eae8bc99-c742-4771-a6e4-c2299b1eb307" xlink:href="nrg-20231231.xsd#nrg_AonHewittAboveMedianYieldCurveDiscountRateYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_nrg_AonHewittAboveMedianYieldCurveDiscountRateYears_eae8bc99-c742-4771-a6e4-c2299b1eb307" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_733189c6-91f0-4c93-bcfe-cd49a55990a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_22fc2416-e6e4-4e8f-866a-1a6047a7bd88" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_733189c6-91f0-4c93-bcfe-cd49a55990a7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_2edd9216-93cf-41c3-af14-812aeac15fbf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_733189c6-91f0-4c93-bcfe-cd49a55990a7" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_2edd9216-93cf-41c3-af14-812aeac15fbf" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsExpectedFutureBenefitPaymentsfortheNextFiveYearsandOtherDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#BenefitPlansandOtherPostretirementBenefitsExpectedFutureBenefitPaymentsfortheNextFiveYearsandOtherDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/BenefitPlansandOtherPostretirementBenefitsExpectedFutureBenefitPaymentsfortheNextFiveYearsandOtherDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_31560e94-c75a-44c8-93d0-57ef52374b12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5ff6b49d-c128-4942-888d-58c6b850c089" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_31560e94-c75a-44c8-93d0-57ef52374b12" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5ff6b49d-c128-4942-888d-58c6b850c089" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_0f93578f-4004-4273-a1db-fc27c0422fff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5ff6b49d-c128-4942-888d-58c6b850c089" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_0f93578f-4004-4273-a1db-fc27c0422fff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_0f93578f-4004-4273-a1db-fc27c0422fff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0f93578f-4004-4273-a1db-fc27c0422fff" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_0f93578f-4004-4273-a1db-fc27c0422fff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_6724536d-e7a8-4372-9665-a176c627a2a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0f93578f-4004-4273-a1db-fc27c0422fff" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_6724536d-e7a8-4372-9665-a176c627a2a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_b40f41e3-80ab-4e0a-9186-839afe8a7351" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_6724536d-e7a8-4372-9665-a176c627a2a1" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_b40f41e3-80ab-4e0a-9186-839afe8a7351" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_340b3679-86c3-49de-a9be-624768fbdf5e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_6724536d-e7a8-4372-9665-a176c627a2a1" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_340b3679-86c3-49de-a9be-624768fbdf5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_262f8c24-1b99-45b2-bf17-475bc2cce366" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5ff6b49d-c128-4942-888d-58c6b850c089" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_262f8c24-1b99-45b2-bf17-475bc2cce366" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_262f8c24-1b99-45b2-bf17-475bc2cce366_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_262f8c24-1b99-45b2-bf17-475bc2cce366" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_262f8c24-1b99-45b2-bf17-475bc2cce366_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_35515b2d-308c-472c-99a3-8978e1847b42" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_262f8c24-1b99-45b2-bf17-475bc2cce366" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_35515b2d-308c-472c-99a3-8978e1847b42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_6de1993d-5845-43cb-a112-d1c85c5b7991" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_35515b2d-308c-472c-99a3-8978e1847b42" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_6de1993d-5845-43cb-a112-d1c85c5b7991" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantAxis_4454b249-64d8-415f-ba41-1f2622882ec1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5ff6b49d-c128-4942-888d-58c6b850c089" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantAxis_4454b249-64d8-415f-ba41-1f2622882ec1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_4454b249-64d8-415f-ba41-1f2622882ec1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_4454b249-64d8-415f-ba41-1f2622882ec1" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_4454b249-64d8-415f-ba41-1f2622882ec1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_b98e4fb6-bdc7-4c6c-8345-af3296b30967" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_4454b249-64d8-415f-ba41-1f2622882ec1" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_b98e4fb6-bdc7-4c6c-8345-af3296b30967" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectUnits1And2Member_e1c0ed4a-f6de-4e1c-96f9-8c77e522a4ea" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectUnits1And2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantDomain_b98e4fb6-bdc7-4c6c-8345-af3296b30967" xlink:to="loc_nrg_SouthTexasProjectUnits1And2Member_e1c0ed4a-f6de-4e1c-96f9-8c77e522a4ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_31560e94-c75a-44c8-93d0-57ef52374b12" xlink:to="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_c9986935-d0fc-4e95-863c-5e86b37dbc4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_c9986935-d0fc-4e95-863c-5e86b37dbc4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_78a9bf9a-9cb2-47c5-bbe0-f44b2984e0df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_78a9bf9a-9cb2-47c5-bbe0-f44b2984e0df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_7d88acb2-9633-4da9-8eb0-a777587b73a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_7d88acb2-9633-4da9-8eb0-a777587b73a5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_614c7b71-1f65-46e2-865e-0eadef625772" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_614c7b71-1f65-46e2-865e-0eadef625772" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_69d9a24a-b1d8-4530-9b26-85580a5914ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_69d9a24a-b1d8-4530-9b26-85580a5914ea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_36a5ade9-896a-434c-9a86-8b054d310708" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_05c849b0-2fe0-43f2-8bb7-c9ab6fcdf047" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_36a5ade9-896a-434c-9a86-8b054d310708" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_31560e94-c75a-44c8-93d0-57ef52374b12" xlink:to="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrescriptionDrugSubsidyReceiptsNextTwelveMonths_735caa8d-ca5b-4a15-9535-af549e459122" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrescriptionDrugSubsidyReceiptsNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:to="loc_us-gaap_PrescriptionDrugSubsidyReceiptsNextTwelveMonths_735caa8d-ca5b-4a15-9535-af549e459122" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearTwo1_2b4ef37b-1534-4d20-82f3-15502d164c79" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrescriptionDrugSubsidyReceiptsYearTwo1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:to="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearTwo1_2b4ef37b-1534-4d20-82f3-15502d164c79" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearThree1_8b3ccbe9-7f70-4124-b249-61469459482f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrescriptionDrugSubsidyReceiptsYearThree1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:to="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearThree1_8b3ccbe9-7f70-4124-b249-61469459482f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearFour1_01fdadd7-c1e5-408e-ac5c-6962a164235a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrescriptionDrugSubsidyReceiptsYearFour1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:to="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearFour1_01fdadd7-c1e5-408e-ac5c-6962a164235a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearFive1_93cff55b-e8ae-4061-a78c-e26f6b8931b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrescriptionDrugSubsidyReceiptsYearFive1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:to="loc_us-gaap_PrescriptionDrugSubsidyReceiptsYearFive1_93cff55b-e8ae-4061-a78c-e26f6b8931b0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrescriptionDrugSubsidyReceiptsAfterYearFive_612cd915-59a4-4c3b-93aa-9603fed3589e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrescriptionDrugSubsidyReceiptsAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PostretirementMedicalPlansWithPrescriptionDrugBenefitsAbstract_b60e9bb1-457a-4853-a6d8-77f2dc312477" xlink:to="loc_us-gaap_PrescriptionDrugSubsidyReceiptsAfterYearFive_612cd915-59a4-4c3b-93aa-9603fed3589e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DefinedBenefitPlansOfAffiliatesAbstract_31142a30-93e6-4282-98d4-b0ea6d42e56b" xlink:href="nrg-20231231.xsd#nrg_DefinedBenefitPlansOfAffiliatesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_31560e94-c75a-44c8-93d0-57ef52374b12" xlink:to="loc_nrg_DefinedBenefitPlansOfAffiliatesAbstract_31142a30-93e6-4282-98d4-b0ea6d42e56b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PercentageOfContributionToRetirementPlanObligationsReimbursedByEntity_44ff5c97-c276-48cb-a59b-21e90a0bc5f1" xlink:href="nrg-20231231.xsd#nrg_PercentageOfContributionToRetirementPlanObligationsReimbursedByEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DefinedBenefitPlansOfAffiliatesAbstract_31142a30-93e6-4282-98d4-b0ea6d42e56b" xlink:to="loc_nrg_PercentageOfContributionToRetirementPlanObligationsReimbursedByEntity_44ff5c97-c276-48cb-a59b-21e90a0bc5f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DefinedBenefitPlanAmountReimbursedToSponsor_a72205bf-cf54-4080-b255-587f86373335" xlink:href="nrg-20231231.xsd#nrg_DefinedBenefitPlanAmountReimbursedToSponsor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DefinedBenefitPlansOfAffiliatesAbstract_31142a30-93e6-4282-98d4-b0ea6d42e56b" xlink:to="loc_nrg_DefinedBenefitPlanAmountReimbursedToSponsor_a72205bf-cf54-4080-b255-587f86373335" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AmountRecognizedInStatementOfFinancialPositionAndAccumulatedOtherComprehensiveIncomeRelatedToEquityMethodInvestmentAbstract_604a4afe-f3e6-4c38-9438-7ad7e598d80d" xlink:href="nrg-20231231.xsd#nrg_AmountRecognizedInStatementOfFinancialPositionAndAccumulatedOtherComprehensiveIncomeRelatedToEquityMethodInvestmentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DefinedBenefitPlansOfAffiliatesAbstract_31142a30-93e6-4282-98d4-b0ea6d42e56b" xlink:to="loc_nrg_AmountRecognizedInStatementOfFinancialPositionAndAccumulatedOtherComprehensiveIncomeRelatedToEquityMethodInvestmentAbstract_604a4afe-f3e6-4c38-9438-7ad7e598d80d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_28eb6225-0489-46e3-97b7-cc4d14abbe22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AmountRecognizedInStatementOfFinancialPositionAndAccumulatedOtherComprehensiveIncomeRelatedToEquityMethodInvestmentAbstract_604a4afe-f3e6-4c38-9438-7ad7e598d80d" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_28eb6225-0489-46e3-97b7-cc4d14abbe22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_3d3bbcae-f127-49b1-8067-483013cd96be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AmountRecognizedInStatementOfFinancialPositionAndAccumulatedOtherComprehensiveIncomeRelatedToEquityMethodInvestmentAbstract_604a4afe-f3e6-4c38-9438-7ad7e598d80d" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_3d3bbcae-f127-49b1-8067-483013cd96be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_e19d3adf-e1bc-4556-a405-cbdb7c93bbcb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_AmountRecognizedInStatementOfFinancialPositionAndAccumulatedOtherComprehensiveIncomeRelatedToEquityMethodInvestmentAbstract_604a4afe-f3e6-4c38-9438-7ad7e598d80d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_e19d3adf-e1bc-4556-a405-cbdb7c93bbcb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DefinedContributionPlansAbstract_0a9d9604-e894-45e5-b14e-6809b7f8b2bc" xlink:href="nrg-20231231.xsd#nrg_DefinedContributionPlansAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_31560e94-c75a-44c8-93d0-57ef52374b12" xlink:to="loc_nrg_DefinedContributionPlansAbstract_0a9d9604-e894-45e5-b14e-6809b7f8b2bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_ac853601-7fa0-407a-bdae-5ed9e31f002d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_DefinedContributionPlansAbstract_0a9d9604-e894-45e5-b14e-6809b7f8b2bc" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_ac853601-7fa0-407a-bdae-5ed9e31f002d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CapitalStructureChangesinNRGsCommonStockIssuedandOutstandingDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#CapitalStructureChangesinNRGsCommonStockIssuedandOutstandingDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CapitalStructureChangesinNRGsCommonStockIssuedandOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_5f62c773-954d-4112-b3e3-3cd91fe4ef4d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_17d4f8ca-ed01-43d5-a5fc-0cfd2e98b79b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_5f62c773-954d-4112-b3e3-3cd91fe4ef4d" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_17d4f8ca-ed01-43d5-a5fc-0cfd2e98b79b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_ec8d6084-d32b-4a9e-bf7f-b9c717f92ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_17d4f8ca-ed01-43d5-a5fc-0cfd2e98b79b" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_ec8d6084-d32b-4a9e-bf7f-b9c717f92ebb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_ec8d6084-d32b-4a9e-bf7f-b9c717f92ebb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_ec8d6084-d32b-4a9e-bf7f-b9c717f92ebb" xlink:to="loc_us-gaap_EquityComponentDomain_ec8d6084-d32b-4a9e-bf7f-b9c717f92ebb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2aa8bdd3-1b4f-4e44-abd2-10e748c702e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_ec8d6084-d32b-4a9e-bf7f-b9c717f92ebb" xlink:to="loc_us-gaap_EquityComponentDomain_2aa8bdd3-1b4f-4e44-abd2-10e748c702e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_02861fee-de40-46dc-b968-1ebb69034cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2aa8bdd3-1b4f-4e44-abd2-10e748c702e6" xlink:to="loc_us-gaap_PreferredStockMember_02861fee-de40-46dc-b968-1ebb69034cb5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_8c937326-4729-46c9-9c08-8b567b062fe0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2aa8bdd3-1b4f-4e44-abd2-10e748c702e6" xlink:to="loc_us-gaap_CommonStockMember_8c937326-4729-46c9-9c08-8b567b062fe0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_0ab4bc58-2a26-42a4-8bc7-e7c859eeed0a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2aa8bdd3-1b4f-4e44-abd2-10e748c702e6" xlink:to="loc_us-gaap_TreasuryStockCommonMember_0ab4bc58-2a26-42a4-8bc7-e7c859eeed0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_7b751d28-a19d-4ec0-b9c8-509155bc4a9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_17d4f8ca-ed01-43d5-a5fc-0cfd2e98b79b" xlink:to="loc_us-gaap_StatementClassOfStockAxis_7b751d28-a19d-4ec0-b9c8-509155bc4a9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7b751d28-a19d-4ec0-b9c8-509155bc4a9c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7b751d28-a19d-4ec0-b9c8-509155bc4a9c" xlink:to="loc_us-gaap_ClassOfStockDomain_7b751d28-a19d-4ec0-b9c8-509155bc4a9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_29c57932-a5e6-4d24-9f1e-5839384c8356" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_7b751d28-a19d-4ec0-b9c8-509155bc4a9c" xlink:to="loc_us-gaap_ClassOfStockDomain_29c57932-a5e6-4d24-9f1e-5839384c8356" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_e77800c0-9703-4fda-a8e5-334b747732fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_29c57932-a5e6-4d24-9f1e-5839384c8356" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_e77800c0-9703-4fda-a8e5-334b747732fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_ea05ca59-99f1-4827-9033-f946eebd3a27" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_17d4f8ca-ed01-43d5-a5fc-0cfd2e98b79b" xlink:to="loc_us-gaap_PlanNameAxis_ea05ca59-99f1-4827-9033-f946eebd3a27" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_ea05ca59-99f1-4827-9033-f946eebd3a27_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_ea05ca59-99f1-4827-9033-f946eebd3a27" xlink:to="loc_us-gaap_PlanNameDomain_ea05ca59-99f1-4827-9033-f946eebd3a27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_8e877b81-cfd3-42d2-a8f4-6f3bf2322da0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_ea05ca59-99f1-4827-9033-f946eebd3a27" xlink:to="loc_us-gaap_PlanNameDomain_8e877b81-cfd3-42d2-a8f4-6f3bf2322da0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LongTermIncentivePlanMember_d50f42df-42b7-47de-a400-0b345bc6827a" xlink:href="nrg-20231231.xsd#nrg_LongTermIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_8e877b81-cfd3-42d2-a8f4-6f3bf2322da0" xlink:to="loc_nrg_LongTermIncentivePlanMember_d50f42df-42b7-47de-a400-0b345bc6827a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmployeeStockPurchasePlanMember_0e7a8b27-e291-42b4-b852-1b71e7f8ed1a" xlink:href="nrg-20231231.xsd#nrg_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_8e877b81-cfd3-42d2-a8f4-6f3bf2322da0" xlink:to="loc_nrg_EmployeeStockPurchasePlanMember_0e7a8b27-e291-42b4-b852-1b71e7f8ed1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_ef88bb5b-eaee-4282-8a4f-b3049015391f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_17d4f8ca-ed01-43d5-a5fc-0cfd2e98b79b" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_ef88bb5b-eaee-4282-8a4f-b3049015391f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ef88bb5b-eaee-4282-8a4f-b3049015391f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ef88bb5b-eaee-4282-8a4f-b3049015391f" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ef88bb5b-eaee-4282-8a4f-b3049015391f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_180b9016-d354-43ca-b1a5-33a90d85e848" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ef88bb5b-eaee-4282-8a4f-b3049015391f" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_180b9016-d354-43ca-b1a5-33a90d85e848" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_f8f29666-ba02-4f54-a5fa-94aa4ad3fe6d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_180b9016-d354-43ca-b1a5-33a90d85e848" xlink:to="loc_us-gaap_SubsequentEventMember_f8f29666-ba02-4f54-a5fa-94aa4ad3fe6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:href="nrg-20231231.xsd#nrg_ScheduleofStockbyClassEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_5f62c773-954d-4112-b3e3-3cd91fe4ef4d" xlink:to="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_e6f7006a-9403-4cbe-b903-3399bace3a54" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_e6f7006a-9403-4cbe-b903-3399bace3a54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_bba83c8e-734a-45c0-b0d0-de242bcdbd46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_PreferredStockSharesIssued_bba83c8e-734a-45c0-b0d0-de242bcdbd46" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_a82c51ca-dc3e-4f5e-94ca-87711e1a58d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_a82c51ca-dc3e-4f5e-94ca-87711e1a58d8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_3157f14e-424b-41b5-a5ea-8e0ba632d484" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_2ae9da3e-0db7-4ca2-883b-9b886b95d0b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_e8511162-64c3-481d-b3ed-70d32a9c9e47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_CommonStockSharesIssued_e8511162-64c3-481d-b3ed-70d32a9c9e47" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_630d157c-890e-4566-b1c2-cd03232cf1a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_TreasuryStockCommonShares_630d157c-890e-4566-b1c2-cd03232cf1a9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_9393adf6-ea45-4759-9657-9b0f47357c72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_9393adf6-ea45-4759-9657-9b0f47357c72" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_87663492-bfeb-474b-b188-47aad82f9808" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_87663492-bfeb-474b-b188-47aad82f9808" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_8640f47a-5eed-439a-ba43-40dc6774f799" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_8640f47a-5eed-439a-ba43-40dc6774f799" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_4e2f3492-8cd3-4fd3-a18c-ca29ad4ce8ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_4e2f3492-8cd3-4fd3-a18c-ca29ad4ce8ea" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesRetired_cc239dd9-c313-4a7b-a130-0220d1536c80" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockSharesRetired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ScheduleofStockbyClassEquityRollForward_bd907962-5900-4d12-b126-a6886c83b5c9" xlink:to="loc_us-gaap_TreasuryStockSharesRetired_cc239dd9-c313-4a7b-a130-0220d1536c80" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_7831e725-09db-4600-9613-c25d09aa8dbd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_6f749609-2ac5-4f96-a67a-c6e4085b82ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_e1b382bb-d0d1-4537-8d22-eac8d3ad2ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CapitalStructureCommonStockShareRepurchasesandRetirementofTreasuryStockDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#CapitalStructureCommonStockShareRepurchasesandRetirementofTreasuryStockDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CapitalStructureCommonStockShareRepurchasesandRetirementofTreasuryStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityClassOfTreasuryStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfTreasuryStockTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_4a35b044-2762-4c75-867f-8812f8ca8862" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:to="loc_us-gaap_FinancialInstrumentAxis_4a35b044-2762-4c75-867f-8812f8ca8862" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4a35b044-2762-4c75-867f-8812f8ca8862_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_4a35b044-2762-4c75-867f-8812f8ca8862" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4a35b044-2762-4c75-867f-8812f8ca8862_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10a7b498-6283-4c25-903b-b3a98e197dce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_4a35b044-2762-4c75-867f-8812f8ca8862" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10a7b498-6283-4c25-903b-b3a98e197dce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_3d6aecf8-3189-4b31-bdfc-6d62275cf642" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10a7b498-6283-4c25-903b-b3a98e197dce" xlink:to="loc_us-gaap_StockCompensationPlanMember_3d6aecf8-3189-4b31-bdfc-6d62275cf642" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_447a22e3-f0c7-444e-ba25-affb732d2589" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:to="loc_srt_RangeAxis_447a22e3-f0c7-444e-ba25-affb732d2589" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_447a22e3-f0c7-444e-ba25-affb732d2589_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_447a22e3-f0c7-444e-ba25-affb732d2589" xlink:to="loc_srt_RangeMember_447a22e3-f0c7-444e-ba25-affb732d2589_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_26b51d66-46ed-474b-8684-0e594fbee740" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_447a22e3-f0c7-444e-ba25-affb732d2589" xlink:to="loc_srt_RangeMember_26b51d66-46ed-474b-8684-0e594fbee740" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_2750a2af-ee95-4bb5-9cf4-9044f4611d35" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_26b51d66-46ed-474b-8684-0e594fbee740" xlink:to="loc_srt_MinimumMember_2750a2af-ee95-4bb5-9cf4-9044f4611d35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_1fa37845-925b-4e27-a7a3-25fc06f11ea3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_26b51d66-46ed-474b-8684-0e594fbee740" xlink:to="loc_srt_MaximumMember_1fa37845-925b-4e27-a7a3-25fc06f11ea3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_9d94769a-2544-4719-a4fd-081096451236" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:to="loc_srt_StatementScenarioAxis_9d94769a-2544-4719-a4fd-081096451236" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_9d94769a-2544-4719-a4fd-081096451236_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_9d94769a-2544-4719-a4fd-081096451236" xlink:to="loc_srt_ScenarioUnspecifiedDomain_9d94769a-2544-4719-a4fd-081096451236_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_259cbefb-e888-440b-ba37-32d0ddbf3610" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_9d94769a-2544-4719-a4fd-081096451236" xlink:to="loc_srt_ScenarioUnspecifiedDomain_259cbefb-e888-440b-ba37-32d0ddbf3610" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScenarioPlanMember_5724831b-ce54-495d-b981-ea9265739437" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScenarioPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_259cbefb-e888-440b-ba37-32d0ddbf3610" xlink:to="loc_us-gaap_ScenarioPlanMember_5724831b-ce54-495d-b981-ea9265739437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_5d1d2fc2-d765-45aa-9745-0668b7607316" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_5d1d2fc2-d765-45aa-9745-0668b7607316" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_5d1d2fc2-d765-45aa-9745-0668b7607316_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5d1d2fc2-d765-45aa-9745-0668b7607316" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_5d1d2fc2-d765-45aa-9745-0668b7607316_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_da3c0527-d8c5-49a2-9825-867e07db5034" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5d1d2fc2-d765-45aa-9745-0668b7607316" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_da3c0527-d8c5-49a2-9825-867e07db5034" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_1da7b27a-127d-4e5b-bbaf-ed297baefd08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_da3c0527-d8c5-49a2-9825-867e07db5034" xlink:to="loc_us-gaap_SubsequentEventMember_1da7b27a-127d-4e5b-bbaf-ed297baefd08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanAxis_952c412c-f92b-4d95-bccc-b176db8a75e2" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:to="loc_nrg_CapitalAllocationPlanAxis_952c412c-f92b-4d95-bccc-b176db8a75e2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanDomain_952c412c-f92b-4d95-bccc-b176db8a75e2_default" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nrg_CapitalAllocationPlanAxis_952c412c-f92b-4d95-bccc-b176db8a75e2" xlink:to="loc_nrg_CapitalAllocationPlanDomain_952c412c-f92b-4d95-bccc-b176db8a75e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanDomain_264d7df8-e50d-40ff-b6c6-708774adedb5" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nrg_CapitalAllocationPlanAxis_952c412c-f92b-4d95-bccc-b176db8a75e2" xlink:to="loc_nrg_CapitalAllocationPlanDomain_264d7df8-e50d-40ff-b6c6-708774adedb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_A2021CapitalAllocationPlanMember_6eb9ef57-eb5a-4a2e-b80d-53e4112bf85e" xlink:href="nrg-20231231.xsd#nrg_A2021CapitalAllocationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CapitalAllocationPlanDomain_264d7df8-e50d-40ff-b6c6-708774adedb5" xlink:to="loc_nrg_A2021CapitalAllocationPlanMember_6eb9ef57-eb5a-4a2e-b80d-53e4112bf85e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlan2023Member_dd8d78b3-53db-4dad-a1b9-2c4ed6169310" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlan2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CapitalAllocationPlanDomain_264d7df8-e50d-40ff-b6c6-708774adedb5" xlink:to="loc_nrg_CapitalAllocationPlan2023Member_dd8d78b3-53db-4dad-a1b9-2c4ed6169310" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanOpenMarketRepurchasesMember_c1146de3-3182-4ac1-8580-64a8cd54abba" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanOpenMarketRepurchasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CapitalAllocationPlanDomain_264d7df8-e50d-40ff-b6c6-708774adedb5" xlink:to="loc_nrg_CapitalAllocationPlanOpenMarketRepurchasesMember_c1146de3-3182-4ac1-8580-64a8cd54abba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_79bad8ae-75b6-4c6a-a67c-dd3a655f2b5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_79bad8ae-75b6-4c6a-a67c-dd3a655f2b5c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_79bad8ae-75b6-4c6a-a67c-dd3a655f2b5c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_79bad8ae-75b6-4c6a-a67c-dd3a655f2b5c" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_79bad8ae-75b6-4c6a-a67c-dd3a655f2b5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_b9b8b58f-8d65-41c2-8618-9c748e21e0de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_79bad8ae-75b6-4c6a-a67c-dd3a655f2b5c" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_b9b8b58f-8d65-41c2-8618-9c748e21e0de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_November2023AcceleratedShareRepurchaseAgreementsMember_1625ab33-9d1e-4b33-a647-6de313dc3bda" xlink:href="nrg-20231231.xsd#nrg_November2023AcceleratedShareRepurchaseAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_b9b8b58f-8d65-41c2-8618-9c748e21e0de" xlink:to="loc_nrg_November2023AcceleratedShareRepurchaseAgreementsMember_1625ab33-9d1e-4b33-a647-6de313dc3bda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_39274d21-3505-48cf-845d-003435eb8388" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_9f275517-9eb2-46f0-b6af-f1a0764dea1a" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_39274d21-3505-48cf-845d-003435eb8388" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_39274d21-3505-48cf-845d-003435eb8388_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_39274d21-3505-48cf-845d-003435eb8388" xlink:to="loc_us-gaap_EquityComponentDomain_39274d21-3505-48cf-845d-003435eb8388_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_6f2a8ba2-7f67-4a57-834d-d93a67d5ef0e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_39274d21-3505-48cf-845d-003435eb8388" xlink:to="loc_us-gaap_EquityComponentDomain_6f2a8ba2-7f67-4a57-834d-d93a67d5ef0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_15926fdf-9340-4bfc-b88a-2a7cb17b24db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6f2a8ba2-7f67-4a57-834d-d93a67d5ef0e" xlink:to="loc_us-gaap_TreasuryStockCommonMember_15926fdf-9340-4bfc-b88a-2a7cb17b24db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_a5a599f9-5217-46ce-b655-c3f87e09afb8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6f2a8ba2-7f67-4a57-834d-d93a67d5ef0e" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_a5a599f9-5217-46ce-b655-c3f87e09afb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_dce8b289-addf-4ecc-96c8-b10cc4bf31d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_dce8b289-addf-4ecc-96c8-b10cc4bf31d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonStockQuarterlyDividendsPerShareCashPaid_36849126-feeb-496d-b985-7a960e26711a" xlink:href="nrg-20231231.xsd#nrg_CommonStockQuarterlyDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_CommonStockQuarterlyDividendsPerShareCashPaid_36849126-feeb-496d-b985-7a960e26711a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareCashPaid_ad16717b-55cd-4794-b8cf-c41d8b719a46" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_CommonStockDividendsPerShareCashPaid_ad16717b-55cd-4794-b8cf-c41d8b719a46" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonStockDividendsProposedAnnualAmountPerShare_74c7e40b-a8fd-440a-ba56-a5de12e7f7b7" xlink:href="nrg-20231231.xsd#nrg_CommonStockDividendsProposedAnnualAmountPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_CommonStockDividendsProposedAnnualAmountPerShare_74c7e40b-a8fd-440a-ba56-a5de12e7f7b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonStockAnnualDividendsIncreaseDecreasePercentage_998d2952-f911-4e8e-b318-3129d69c76c0" xlink:href="nrg-20231231.xsd#nrg_CommonStockAnnualDividendsIncreaseDecreasePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_CommonStockAnnualDividendsIncreaseDecreasePercentage_998d2952-f911-4e8e-b318-3129d69c76c0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonStockAnnualDividendGrowthRate_930b9a12-4ef9-4133-9d1f-f51d5644ba64" xlink:href="nrg-20231231.xsd#nrg_CommonStockAnnualDividendGrowthRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_CommonStockAnnualDividendGrowthRate_930b9a12-4ef9-4133-9d1f-f51d5644ba64" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_f572dafa-2c76-45ec-bc56-7ff02ac832a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_f572dafa-2c76-45ec-bc56-7ff02ac832a2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmployeeStockPurchasePlanMinimumPercentageofCompensationEligible_090ffce3-73a0-41c6-a98f-e0776c404a5c" xlink:href="nrg-20231231.xsd#nrg_EmployeeStockPurchasePlanMinimumPercentageofCompensationEligible"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_EmployeeStockPurchasePlanMinimumPercentageofCompensationEligible_090ffce3-73a0-41c6-a98f-e0776c404a5c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmployeeStockPurchasePlanMaximumPercentageOfCompensationEligible_780360c4-e99d-4f29-b426-872fc66876d8" xlink:href="nrg-20231231.xsd#nrg_EmployeeStockPurchasePlanMaximumPercentageOfCompensationEligible"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_EmployeeStockPurchasePlanMaximumPercentageOfCompensationEligible_780360c4-e99d-4f29-b426-872fc66876d8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_2dfa84a4-7417-4ec4-b63f-1b25ea453ca0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_2dfa84a4-7417-4ec4-b63f-1b25ea453ca0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EmployeeStockPurchasePlanExercisePriceAsPercentageOfFairValue_2dec1eff-032c-4a50-b927-13cbf0a1511d" xlink:href="nrg-20231231.xsd#nrg_EmployeeStockPurchasePlanExercisePriceAsPercentageOfFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_EmployeeStockPurchasePlanExercisePriceAsPercentageOfFairValue_2dec1eff-032c-4a50-b927-13cbf0a1511d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonStockCapitalSharesAvailableForEmployeeStockPurchasePlanIncreaseDecrease_4b3e0125-5ded-4704-87c2-dfb0c9464270" xlink:href="nrg-20231231.xsd#nrg_CommonStockCapitalSharesAvailableForEmployeeStockPurchasePlanIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_CommonStockCapitalSharesAvailableForEmployeeStockPurchasePlanIncreaseDecrease_4b3e0125-5ded-4704-87c2-dfb0c9464270" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CommonStockCapitalSharesReservedForEmployeeStockPurchasePlan_8b1d9afe-4ae5-4048-9f6a-f8e4eb21978a" xlink:href="nrg-20231231.xsd#nrg_CommonStockCapitalSharesReservedForEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_CommonStockCapitalSharesReservedForEmployeeStockPurchasePlan_8b1d9afe-4ae5-4048-9f6a-f8e4eb21978a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_0d713c0a-ef26-474a-bc28-2c9545bb1872" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_0d713c0a-ef26-474a-bc28-2c9545bb1872" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPolicyTargetAllocationReturnToShareholdersPercentageOfNetCashAvailableMinimum_db76ab87-1b39-4c72-aded-ce7106b52741" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPolicyTargetAllocationReturnToShareholdersPercentageOfNetCashAvailableMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_CapitalAllocationPolicyTargetAllocationReturnToShareholdersPercentageOfNetCashAvailableMinimum_db76ab87-1b39-4c72-aded-ce7106b52741" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AcceleratedShareRepurchasesAgreementAmount_fe2ae7ab-b280-40ff-b669-eef33f5a8ffc" xlink:href="nrg-20231231.xsd#nrg_AcceleratedShareRepurchasesAgreementAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_nrg_AcceleratedShareRepurchasesAgreementAmount_fe2ae7ab-b280-40ff-b669-eef33f5a8ffc" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt_faa1c530-bab1-47c2-b741-d3db10ce06df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt_faa1c530-bab1-47c2-b741-d3db10ce06df" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_573e9747-74ae-4db5-b7a6-27a880fb2597" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_573e9747-74ae-4db5-b7a6-27a880fb2597" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_c7ba3295-99de-422d-bc0c-5fbdae4689a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_c7ba3295-99de-422d-bc0c-5fbdae4689a7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_f9c05e95-8197-4584-bd57-f583bb531ffe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_f9c05e95-8197-4584-bd57-f583bb531ffe" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_e5b1bb60-0c37-418f-92f1-65240b1f2f03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_e5b1bb60-0c37-418f-92f1-65240b1f2f03" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_cc40ef3c-e349-42a2-a4d4-e9d074b875db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_cc40ef3c-e349-42a2-a4d4-e9d074b875db" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesRetired_e40f5020-0a95-4ac2-86f6-5050a7fbd26e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockSharesRetired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_TreasuryStockSharesRetired_e40f5020-0a95-4ac2-86f6-5050a7fbd26e" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_3c051c8a-431c-4278-8d34-0f6fff3aebd1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockRetiredCostMethodAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_cb8ef68c-6c72-4186-b024-19093b1fc371" xlink:to="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_3c051c8a-431c-4278-8d34-0f6fff3aebd1" xlink:type="arc" order="23"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CapitalStructureSummaryofChangesinSharesRepurchasedDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#CapitalStructureSummaryofChangesinSharesRepurchasedDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CapitalStructureSummaryofChangesinSharesRepurchasedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCapitalizationEquityLineItems_ac7c5f1e-aa30-47c3-9416-0c191e84beef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfCapitalizationEquityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCapitalizationEquityTable_eb8977bc-5941-4e9b-b513-ea5ef094dba3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfCapitalizationEquityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityLineItems_ac7c5f1e-aa30-47c3-9416-0c191e84beef" xlink:to="loc_us-gaap_ScheduleOfCapitalizationEquityTable_eb8977bc-5941-4e9b-b513-ea5ef094dba3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanAxis_7e53cd34-79db-4009-a4d0-8e6261f8d0ae" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityTable_eb8977bc-5941-4e9b-b513-ea5ef094dba3" xlink:to="loc_nrg_CapitalAllocationPlanAxis_7e53cd34-79db-4009-a4d0-8e6261f8d0ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanDomain_7e53cd34-79db-4009-a4d0-8e6261f8d0ae_default" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_nrg_CapitalAllocationPlanAxis_7e53cd34-79db-4009-a4d0-8e6261f8d0ae" xlink:to="loc_nrg_CapitalAllocationPlanDomain_7e53cd34-79db-4009-a4d0-8e6261f8d0ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanDomain_2ea17402-82a6-4ce9-9bf0-9cfb9cf970eb" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_nrg_CapitalAllocationPlanAxis_7e53cd34-79db-4009-a4d0-8e6261f8d0ae" xlink:to="loc_nrg_CapitalAllocationPlanDomain_2ea17402-82a6-4ce9-9bf0-9cfb9cf970eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanOpenMarketRepurchasesMember_a5c2e6a8-d024-4b66-956b-6e44ab747017" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanOpenMarketRepurchasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CapitalAllocationPlanDomain_2ea17402-82a6-4ce9-9bf0-9cfb9cf970eb" xlink:to="loc_nrg_CapitalAllocationPlanOpenMarketRepurchasesMember_a5c2e6a8-d024-4b66-956b-6e44ab747017" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanAcceleratedRepurchaseAgreementsMember_92c56e9a-2214-4f81-ba76-d8f002c7f4ee" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanAcceleratedRepurchaseAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CapitalAllocationPlanDomain_2ea17402-82a6-4ce9-9bf0-9cfb9cf970eb" xlink:to="loc_nrg_CapitalAllocationPlanAcceleratedRepurchaseAgreementsMember_92c56e9a-2214-4f81-ba76-d8f002c7f4ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalAllocationPlanMember_a577cfb7-2f0d-420d-90ed-80e5fe32305c" xlink:href="nrg-20231231.xsd#nrg_CapitalAllocationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_CapitalAllocationPlanDomain_2ea17402-82a6-4ce9-9bf0-9cfb9cf970eb" xlink:to="loc_nrg_CapitalAllocationPlanMember_a577cfb7-2f0d-420d-90ed-80e5fe32305c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_ff635cc8-7d20-4929-8b84-3df03445bccc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityTable_eb8977bc-5941-4e9b-b513-ea5ef094dba3" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_ff635cc8-7d20-4929-8b84-3df03445bccc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ff635cc8-7d20-4929-8b84-3df03445bccc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ff635cc8-7d20-4929-8b84-3df03445bccc" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ff635cc8-7d20-4929-8b84-3df03445bccc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_a23f3c33-0c49-402f-851e-7c868b6c2a49" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ff635cc8-7d20-4929-8b84-3df03445bccc" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_a23f3c33-0c49-402f-851e-7c868b6c2a49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_e27f8927-1306-48a4-9bb7-cc658308d314" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_a23f3c33-0c49-402f-851e-7c868b6c2a49" xlink:to="loc_us-gaap_SubsequentEventMember_e27f8927-1306-48a4-9bb7-cc658308d314" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_af915d14-32a0-4d0a-8f8c-9e48c1612de1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityLineItems_ac7c5f1e-aa30-47c3-9416-0c191e84beef" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_af915d14-32a0-4d0a-8f8c-9e48c1612de1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_0ed65ec8-9aaa-44d6-9599-165501a0ba5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityLineItems_ac7c5f1e-aa30-47c3-9416-0c191e84beef" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_0ed65ec8-9aaa-44d6-9599-165501a0ba5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_503bc6f5-2fe2-47e1-b243-98a2b60178d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityLineItems_ac7c5f1e-aa30-47c3-9416-0c191e84beef" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_503bc6f5-2fe2-47e1-b243-98a2b60178d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccruedLiabilitiesStockRepurchases_fc9c4b57-14b1-449b-b68d-0c0d868e13e2" xlink:href="nrg-20231231.xsd#nrg_AccruedLiabilitiesStockRepurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityLineItems_ac7c5f1e-aa30-47c3-9416-0c191e84beef" xlink:to="loc_nrg_AccruedLiabilitiesStockRepurchases_fc9c4b57-14b1-449b-b68d-0c0d868e13e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TreasuryStockValueAcquiredCostMethodExciseTax_601311e5-be72-49ca-aea5-4b1871057865" xlink:href="nrg-20231231.xsd#nrg_TreasuryStockValueAcquiredCostMethodExciseTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfCapitalizationEquityLineItems_ac7c5f1e-aa30-47c3-9416-0c191e84beef" xlink:to="loc_nrg_TreasuryStockValueAcquiredCostMethodExciseTax_601311e5-be72-49ca-aea5-4b1871057865" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CapitalStructurePreferredStockDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#CapitalStructurePreferredStockDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CapitalStructurePreferredStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_58104ce5-95dc-48ed-84aa-eaf490938c35" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_58104ce5-95dc-48ed-84aa-eaf490938c35" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_0a31adb1-a1c8-4416-9d1a-f2e2a412fe67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_58104ce5-95dc-48ed-84aa-eaf490938c35" xlink:to="loc_us-gaap_StatementClassOfStockAxis_0a31adb1-a1c8-4416-9d1a-f2e2a412fe67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0a31adb1-a1c8-4416-9d1a-f2e2a412fe67_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0a31adb1-a1c8-4416-9d1a-f2e2a412fe67" xlink:to="loc_us-gaap_ClassOfStockDomain_0a31adb1-a1c8-4416-9d1a-f2e2a412fe67_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_d217ebb6-2ec0-4b33-869a-57654493f948" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0a31adb1-a1c8-4416-9d1a-f2e2a412fe67" xlink:to="loc_us-gaap_ClassOfStockDomain_d217ebb6-2ec0-4b33-869a-57654493f948" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_f240ba09-d52d-489b-b93a-30a639387476" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_d217ebb6-2ec0-4b33-869a-57654493f948" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_f240ba09-d52d-489b-b93a-30a639387476" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_d35a1398-191d-440c-b6b9-0594f3ce08cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_58104ce5-95dc-48ed-84aa-eaf490938c35" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_d35a1398-191d-440c-b6b9-0594f3ce08cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_d35a1398-191d-440c-b6b9-0594f3ce08cc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d35a1398-191d-440c-b6b9-0594f3ce08cc" xlink:to="loc_us-gaap_EquityComponentDomain_d35a1398-191d-440c-b6b9-0594f3ce08cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_712729e0-bd3a-4053-9050-5af05b748df9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_d35a1398-191d-440c-b6b9-0594f3ce08cc" xlink:to="loc_us-gaap_EquityComponentDomain_712729e0-bd3a-4053-9050-5af05b748df9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_9d1529a0-8d3b-484b-bbd3-ab2b78063b23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_712729e0-bd3a-4053-9050-5af05b748df9" xlink:to="loc_us-gaap_PreferredStockMember_9d1529a0-8d3b-484b-bbd3-ab2b78063b23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_5d3d4db0-662d-49ff-8f0d-d1c4bc4911db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_58104ce5-95dc-48ed-84aa-eaf490938c35" xlink:to="loc_us-gaap_VariableRateAxis_5d3d4db0-662d-49ff-8f0d-d1c4bc4911db" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_5d3d4db0-662d-49ff-8f0d-d1c4bc4911db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_5d3d4db0-662d-49ff-8f0d-d1c4bc4911db" xlink:to="loc_us-gaap_VariableRateDomain_5d3d4db0-662d-49ff-8f0d-d1c4bc4911db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_eae31032-6951-4d1e-96f7-76a7794d652a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_5d3d4db0-662d-49ff-8f0d-d1c4bc4911db" xlink:to="loc_us-gaap_VariableRateDomain_eae31032-6951-4d1e-96f7-76a7794d652a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UsTreasuryUstInterestRateMember_7a17b877-89a6-4b79-83b6-fee36e7178f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UsTreasuryUstInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_eae31032-6951-4d1e-96f7-76a7794d652a" xlink:to="loc_us-gaap_UsTreasuryUstInterestRateMember_7a17b877-89a6-4b79-83b6-fee36e7178f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_2682e679-0f53-4b52-9a56-c33057445c30" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_2682e679-0f53-4b52-9a56-c33057445c30" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_54ba85f1-7928-4521-bd17-aaa6dc4bba15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_54ba85f1-7928-4521-bd17-aaa6dc4bba15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_b6593594-2302-437c-9887-56f517c50bba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_b6593594-2302-437c-9887-56f517c50bba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockLiquidationPreference_3d8e72de-f9e7-40df-bcb5-1c448be2b896" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockLiquidationPreference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_us-gaap_PreferredStockLiquidationPreference_3d8e72de-f9e7-40df-bcb5-1c448be2b896" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PreferredStockDividendRateFloorPercentage_9ca7fbdf-5fc3-4168-bfce-0ab2e713c45e" xlink:href="nrg-20231231.xsd#nrg_PreferredStockDividendRateFloorPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_nrg_PreferredStockDividendRateFloorPercentage_9ca7fbdf-5fc3-4168-bfce-0ab2e713c45e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PreferredStockDividendRateBasisSpreadOnVariableRate_05ee6614-8269-45ae-b422-6dfd8eec2737" xlink:href="nrg-20231231.xsd#nrg_PreferredStockDividendRateBasisSpreadOnVariableRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_nrg_PreferredStockDividendRateBasisSpreadOnVariableRate_05ee6614-8269-45ae-b422-6dfd8eec2737" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_b82d94c0-085c-4177-bc97-46cc4ae7aa68" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_b82d94c0-085c-4177-bc97-46cc4ae7aa68" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockCash_db5d6e2a-2505-4ad9-ba3d-fac0c7ca3fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPreferredStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_198e45bb-8d4c-46d6-857c-0d67c104c754" xlink:to="loc_us-gaap_DividendsPreferredStockCash_db5d6e2a-2505-4ad9-ba3d-fac0c7ca3fb0" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesSummaryofEquityMethodInvestmentsandUndistributedEarningsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesSummaryofEquityMethodInvestmentsandUndistributedEarningsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesSummaryofEquityMethodInvestmentsandUndistributedEarningsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_6eeac17d-d109-4c18-9232-2d96054b9b8b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_006c05bb-f6d4-4698-ab7f-d75baa270241" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_6eeac17d-d109-4c18-9232-2d96054b9b8b" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_006c05bb-f6d4-4698-ab7f-d75baa270241" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_1b9223e7-7aeb-4f2f-9dd0-0fe8c8dd7c05" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_006c05bb-f6d4-4698-ab7f-d75baa270241" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_1b9223e7-7aeb-4f2f-9dd0-0fe8c8dd7c05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_1b9223e7-7aeb-4f2f-9dd0-0fe8c8dd7c05_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_1b9223e7-7aeb-4f2f-9dd0-0fe8c8dd7c05" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_1b9223e7-7aeb-4f2f-9dd0-0fe8c8dd7c05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_fcd40239-bcc4-48bc-8973-82bff701f19e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_1b9223e7-7aeb-4f2f-9dd0-0fe8c8dd7c05" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_fcd40239-bcc4-48bc-8973-82bff701f19e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GladstonePowerStationMember_99cdca25-6508-420f-8710-70ca8f5c58c3" xlink:href="nrg-20231231.xsd#nrg_GladstonePowerStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_fcd40239-bcc4-48bc-8973-82bff701f19e" xlink:to="loc_nrg_GladstonePowerStationMember_99cdca25-6508-420f-8710-70ca8f5c58c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MidwaySunsetCogenerationCompanyMember_ba8601c9-4351-4633-9373-c90383dc79e4" xlink:href="nrg-20231231.xsd#nrg_MidwaySunsetCogenerationCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_fcd40239-bcc4-48bc-8973-82bff701f19e" xlink:to="loc_nrg_MidwaySunsetCogenerationCompanyMember_ba8601c9-4351-4633-9373-c90383dc79e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_212b2a31-0e5f-46c3-861e-0958c621c386" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_6eeac17d-d109-4c18-9232-2d96054b9b8b" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_212b2a31-0e5f-46c3-861e-0958c621c386" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_744ed320-cdc5-43a9-a460-c6be42d15078" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_6eeac17d-d109-4c18-9232-2d96054b9b8b" xlink:to="loc_us-gaap_EquityMethodInvestments_744ed320-cdc5-43a9-a460-c6be42d15078" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees_383adb16-6df7-472d-b39b-e80c679b4eab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_6eeac17d-d109-4c18-9232-2d96054b9b8b" xlink:to="loc_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees_383adb16-6df7-472d-b39b-e80c679b4eab" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesOtherEquityInvestmentsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesOtherEquityInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesOtherEquityInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_39de69b1-258e-4c99-9b4c-71181ba125d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_f8a5a72d-2aa8-43c8-aa1f-5df6f27fa924" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_39de69b1-258e-4c99-9b4c-71181ba125d0" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_f8a5a72d-2aa8-43c8-aa1f-5df6f27fa924" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_cb842fd1-92a9-4322-a53e-9a1a1e55229b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_f8a5a72d-2aa8-43c8-aa1f-5df6f27fa924" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_cb842fd1-92a9-4322-a53e-9a1a1e55229b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_cb842fd1-92a9-4322-a53e-9a1a1e55229b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_cb842fd1-92a9-4322-a53e-9a1a1e55229b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_cb842fd1-92a9-4322-a53e-9a1a1e55229b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_403ac2c2-8415-4010-a415-3cc8eb26af13" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_cb842fd1-92a9-4322-a53e-9a1a1e55229b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_403ac2c2-8415-4010-a415-3cc8eb26af13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GladstonePowerStationMember_a92cdc3f-235a-4aaa-a110-9166329e5617" xlink:href="nrg-20231231.xsd#nrg_GladstonePowerStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_403ac2c2-8415-4010-a415-3cc8eb26af13" xlink:to="loc_nrg_GladstonePowerStationMember_a92cdc3f-235a-4aaa-a110-9166329e5617" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_2208d9e7-323b-4793-b6b5-76bad11871cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_39de69b1-258e-4c99-9b4c-71181ba125d0" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_2208d9e7-323b-4793-b6b5-76bad11871cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PowerGenerationCapacityMegawatts_dc227d8b-0e43-430d-9131-03719e2b0e6b" xlink:href="nrg-20231231.xsd#nrg_PowerGenerationCapacityMegawatts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_39de69b1-258e-4c99-9b4c-71181ba125d0" xlink:to="loc_nrg_PowerGenerationCapacityMegawatts_dc227d8b-0e43-430d-9131-03719e2b0e6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_92529dab-65a6-4a8a-8616-5ac870b78f19" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_39de69b1-258e-4c99-9b4c-71181ba125d0" xlink:to="loc_us-gaap_EquityMethodInvestments_92529dab-65a6-4a8a-8616-5ac870b78f19" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesSummarizedFinancialInformationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesSummarizedFinancialInformationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/InvestmentsAccountedforbytheEquityMethodandVariableInterestEntitiesSummarizedFinancialInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_13f6cec6-3f4b-4ee9-8e59-a654680d97db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_41ad6069-b142-42e0-8647-a78d07424941" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_13f6cec6-3f4b-4ee9-8e59-a654680d97db" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_41ad6069-b142-42e0-8647-a78d07424941" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_db737a60-6ffc-43be-ba62-d7d48b23d8af" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_41ad6069-b142-42e0-8647-a78d07424941" xlink:to="loc_srt_ConsolidatedEntitiesAxis_db737a60-6ffc-43be-ba62-d7d48b23d8af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_db737a60-6ffc-43be-ba62-d7d48b23d8af_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_db737a60-6ffc-43be-ba62-d7d48b23d8af" xlink:to="loc_srt_ConsolidatedEntitiesDomain_db737a60-6ffc-43be-ba62-d7d48b23d8af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_52bc55d4-a2f1-4a64-8ac7-3c69c2128bd1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_db737a60-6ffc-43be-ba62-d7d48b23d8af" xlink:to="loc_srt_ConsolidatedEntitiesDomain_52bc55d4-a2f1-4a64-8ac7-3c69c2128bd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_3a435d98-f41e-458f-a62b-48b887bce212" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_52bc55d4-a2f1-4a64-8ac7-3c69c2128bd1" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_3a435d98-f41e-458f-a62b-48b887bce212" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AccountsReceivableAfterAllowanceForCreditLossAndOtherAssetsCurrent_f0c89885-c9e6-4ce3-aee6-813d247190eb" xlink:href="nrg-20231231.xsd#nrg_AccountsReceivableAfterAllowanceForCreditLossAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_13f6cec6-3f4b-4ee9-8e59-a654680d97db" xlink:to="loc_nrg_AccountsReceivableAfterAllowanceForCreditLossAndOtherAssetsCurrent_f0c89885-c9e6-4ce3-aee6-813d247190eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_78b2ce7f-e925-45ab-9474-1fafe8c8ca12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_13f6cec6-3f4b-4ee9-8e59-a654680d97db" xlink:to="loc_us-gaap_LiabilitiesCurrent_78b2ce7f-e925-45ab-9474-1fafe8c8ca12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNet_3ce431dd-6f44-451a-b3ea-b0421042c9ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_13f6cec6-3f4b-4ee9-8e59-a654680d97db" xlink:to="loc_us-gaap_AssetsNet_3ce431dd-6f44-451a-b3ea-b0421042c9ea" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/SegmentReportingDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#SegmentReportingDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/SegmentReportingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_d41741fa-508d-4fc5-b691-5f29350e2583" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c639b1e5-0678-4ac2-9c59-f5aea33f5306" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_d41741fa-508d-4fc5-b691-5f29350e2583" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c639b1e5-0678-4ac2-9c59-f5aea33f5306" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_2ee2b9a5-8841-413f-a1a2-c0085badcca7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c639b1e5-0678-4ac2-9c59-f5aea33f5306" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_2ee2b9a5-8841-413f-a1a2-c0085badcca7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_2ee2b9a5-8841-413f-a1a2-c0085badcca7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2ee2b9a5-8841-413f-a1a2-c0085badcca7" xlink:to="loc_us-gaap_SegmentDomain_2ee2b9a5-8841-413f-a1a2-c0085badcca7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4f64b94e-e87a-4406-86b9-99cf4ecc43ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2ee2b9a5-8841-413f-a1a2-c0085badcca7" xlink:to="loc_us-gaap_SegmentDomain_4f64b94e-e87a-4406-86b9-99cf4ecc43ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_TexasSegmentMember_c9ae7825-7b72-4a7d-bd39-aeeae1bdb5f7" xlink:href="nrg-20231231.xsd#nrg_TexasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4f64b94e-e87a-4406-86b9-99cf4ecc43ae" xlink:to="loc_nrg_TexasSegmentMember_c9ae7825-7b72-4a7d-bd39-aeeae1bdb5f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_EastSegmentMember_725f3eb3-335f-4d41-8fd4-068faa1ec9c4" xlink:href="nrg-20231231.xsd#nrg_EastSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4f64b94e-e87a-4406-86b9-99cf4ecc43ae" xlink:to="loc_nrg_EastSegmentMember_725f3eb3-335f-4d41-8fd4-068faa1ec9c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_WestAndOtherSegmentMember_9e27c761-a742-40f8-ab03-dd4579ee5f2b" xlink:href="nrg-20231231.xsd#nrg_WestAndOtherSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4f64b94e-e87a-4406-86b9-99cf4ecc43ae" xlink:to="loc_nrg_WestAndOtherSegmentMember_9e27c761-a742-40f8-ab03-dd4579ee5f2b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSmartHomeIncMember_dc4f52c6-b880-49d4-bab0-a2fc4bba13c8" xlink:href="nrg-20231231.xsd#nrg_VivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4f64b94e-e87a-4406-86b9-99cf4ecc43ae" xlink:to="loc_nrg_VivintSmartHomeIncMember_dc4f52c6-b880-49d4-bab0-a2fc4bba13c8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_c7164ef7-db64-449e-931e-a92673cb266f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c639b1e5-0678-4ac2-9c59-f5aea33f5306" xlink:to="loc_srt_ConsolidationItemsAxis_c7164ef7-db64-449e-931e-a92673cb266f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_c7164ef7-db64-449e-931e-a92673cb266f_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_c7164ef7-db64-449e-931e-a92673cb266f" xlink:to="loc_srt_ConsolidationItemsDomain_c7164ef7-db64-449e-931e-a92673cb266f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_e7336d34-05af-45f8-bf8c-c59790ed50c6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_c7164ef7-db64-449e-931e-a92673cb266f" xlink:to="loc_srt_ConsolidationItemsDomain_e7336d34-05af-45f8-bf8c-c59790ed50c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_6cf70a5e-768a-445b-ba88-18fc9e0e9ece" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_e7336d34-05af-45f8-bf8c-c59790ed50c6" xlink:to="loc_us-gaap_OperatingSegmentsMember_6cf70a5e-768a-445b-ba88-18fc9e0e9ece" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_5c1fe7a1-40d7-42ce-ab57-e8703e9d9be2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_e7336d34-05af-45f8-bf8c-c59790ed50c6" xlink:to="loc_us-gaap_CorporateNonSegmentMember_5c1fe7a1-40d7-42ce-ab57-e8703e9d9be2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_6827f46d-42c4-45ec-a901-7c948ed6deb8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_e7336d34-05af-45f8-bf8c-c59790ed50c6" xlink:to="loc_us-gaap_IntersegmentEliminationMember_6827f46d-42c4-45ec-a901-7c948ed6deb8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_d41741fa-508d-4fc5-b691-5f29350e2583" xlink:to="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_6e5c3f9d-b6ac-4da8-beb9-e79912c1ec1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_Revenues_6e5c3f9d-b6ac-4da8-beb9-e79912c1ec1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_Costofrevenueincludingsellingmarketingandgeneraladministrative_a8018663-f90f-4035-b5a1-3be08ed9e6c0" xlink:href="nrg-20231231.xsd#nrg_Costofrevenueincludingsellingmarketingandgeneraladministrative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_nrg_Costofrevenueincludingsellingmarketingandgeneraladministrative_a8018663-f90f-4035-b5a1-3be08ed9e6c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_cc01fd3b-1b67-4ba9-ab60-571872f9cb09" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_cc01fd3b-1b67-4ba9-ab60-571872f9cb09" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_2ff24461-6517-42a6-8227-d82f2851776c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_AssetImpairmentCharges_2ff24461-6517-42a6-8227-d82f2851776c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_adc6fb6f-4afb-46da-9ef7-2575c3261925" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_CostsAndExpenses_adc6fb6f-4afb-46da-9ef7-2575c3261925" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfOtherAssets_ba99a2fb-ebda-46b8-9aba-b00039448b11" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_GainLossOnSaleOfOtherAssets_ba99a2fb-ebda-46b8-9aba-b00039448b11" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_46987ee0-cc0b-4da8-919d-9065d0342e60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_OperatingIncomeLoss_46987ee0-cc0b-4da8-919d-9065d0342e60" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_62e5fe33-ce66-4f64-bf49-66100cdf9fae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_62e5fe33-ce66-4f64-bf49-66100cdf9fae" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_d6340372-9fca-46dc-a6ba-11e54246a6e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_d6340372-9fca-46dc-a6ba-11e54246a6e4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_78a2fbc6-4624-4273-8ba9-64d6e629c0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_78a2fbc6-4624-4273-8ba9-64d6e629c0f1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_ccaa5d91-7992-4228-9fc9-4e35175944e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_ccaa5d91-7992-4228-9fc9-4e35175944e3" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_75d83fd5-45c4-4b1d-be74-8e900f52c48f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_InterestExpense_75d83fd5-45c4-4b1d-be74-8e900f52c48f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_b4ca17bb-096f-4635-a8c2-dc4994210a77" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_b4ca17bb-096f-4635-a8c2-dc4994210a77" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_3628988c-230f-430a-9f06-baf8bd7db78c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_3628988c-230f-430a-9f06-baf8bd7db78c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_bcb47c2c-a7e8-4cad-a25c-b1a0e5103f57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract_25843828-4c34-4e11-a7b3-49a6a21d89d7" xlink:to="loc_us-gaap_NetIncomeLoss_bcb47c2c-a7e8-4cad-a25c-b1a0e5103f57" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_a21764e9-5d26-4e9b-ba45-d6c82f0d235f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationAdditionalInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_d41741fa-508d-4fc5-b691-5f29350e2583" xlink:to="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_a21764e9-5d26-4e9b-ba45-d6c82f0d235f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_9e444be8-18a9-4434-b230-84f11c94cad5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_a21764e9-5d26-4e9b-ba45-d6c82f0d235f" xlink:to="loc_us-gaap_EquityMethodInvestments_9e444be8-18a9-4434-b230-84f11c94cad5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CapitalExpenditures_ce74f837-8f97-42bd-8042-077716d4b5e8" xlink:href="nrg-20231231.xsd#nrg_CapitalExpenditures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_a21764e9-5d26-4e9b-ba45-d6c82f0d235f" xlink:to="loc_nrg_CapitalExpenditures_ce74f837-8f97-42bd-8042-077716d4b5e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_4607d844-c756-4bf6-b9c5-41819227b681" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_a21764e9-5d26-4e9b-ba45-d6c82f0d235f" xlink:to="loc_us-gaap_Goodwill_4607d844-c756-4bf6-b9c5-41819227b681" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_0aaf2d1d-ae57-4c6d-b44b-b1cb8420ca15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationAdditionalInformationAbstract_a21764e9-5d26-4e9b-ba45-d6c82f0d235f" xlink:to="loc_us-gaap_Assets_0aaf2d1d-ae57-4c6d-b44b-b1cb8420ca15" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/IncomeTaxesNarrativeforDeferredTaxAssetsandValuationAllowanceTaxesReceivableandPayableDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#IncomeTaxesNarrativeforDeferredTaxAssetsandValuationAllowanceTaxesReceivableandPayableDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/IncomeTaxesNarrativeforDeferredTaxAssetsandValuationAllowanceTaxesReceivableandPayableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_feb349d1-c23f-475c-a735-1a43bc07cc0c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_feb349d1-c23f-475c-a735-1a43bc07cc0c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_76efa844-0670-4efc-ba10-0a138cf03455" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_feb349d1-c23f-475c-a735-1a43bc07cc0c" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_76efa844-0670-4efc-ba10-0a138cf03455" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_76efa844-0670-4efc-ba10-0a138cf03455_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_76efa844-0670-4efc-ba10-0a138cf03455" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_76efa844-0670-4efc-ba10-0a138cf03455_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_59520a07-fec0-4854-a6b3-ef52b23d2706" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_76efa844-0670-4efc-ba10-0a138cf03455" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_59520a07-fec0-4854-a6b3-ef52b23d2706" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_c8b1221c-b8f6-481f-bbd6-125df81c6e02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_59520a07-fec0-4854-a6b3-ef52b23d2706" xlink:to="loc_us-gaap_DomesticCountryMember_c8b1221c-b8f6-481f-bbd6-125df81c6e02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_9638f2f6-91cf-49b2-9898-d58f22b1327c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_59520a07-fec0-4854-a6b3-ef52b23d2706" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_9638f2f6-91cf-49b2-9898-d58f22b1327c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_5ae30105-1268-489a-9247-14625804c028" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_59520a07-fec0-4854-a6b3-ef52b23d2706" xlink:to="loc_us-gaap_ForeignCountryMember_5ae30105-1268-489a-9247-14625804c028" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_bc5081cc-a382-477d-b33f-b4eb5f2305a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_bc5081cc-a382-477d-b33f-b4eb5f2305a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DeferredTaxAssetNetOfDeferredTaxLiabilityBeforeValuationAllowance_a4cb263d-3c16-47a1-981d-a9da585330ad" xlink:href="nrg-20231231.xsd#nrg_DeferredTaxAssetNetOfDeferredTaxLiabilityBeforeValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:to="loc_nrg_DeferredTaxAssetNetOfDeferredTaxLiabilityBeforeValuationAllowance_a4cb263d-3c16-47a1-981d-a9da585330ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_b6ae093a-6c40-4741-9588-1073b9fd9560" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:to="loc_us-gaap_OperatingLossCarryforwards_b6ae093a-6c40-4741-9588-1073b9fd9560" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_22b1d31c-5c4b-40f5-87e6-56224f2136ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_22b1d31c-5c4b-40f5-87e6-56224f2136ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedIncomeTaxesCurrent_21aac06d-264a-4321-9f98-dbf00e1d2eec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccruedIncomeTaxesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:to="loc_us-gaap_AccruedIncomeTaxesCurrent_21aac06d-264a-4321-9f98-dbf00e1d2eec" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_46d12295-3b38-47d5-8100-683e810532e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_8826b15d-23e6-4c2b-ae32-ef8e2f99ed3e" xlink:to="loc_us-gaap_IncomeTaxesReceivable_46d12295-3b38-47d5-8100-683e810532e3" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationLongTermIncentivePlanDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationLongTermIncentivePlanDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationLongTermIncentivePlanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ff4c0dea-d112-4d78-8ddd-5f9c8ee2c65b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3739cad-055f-4231-b901-4f04edcb05a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ff4c0dea-d112-4d78-8ddd-5f9c8ee2c65b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3739cad-055f-4231-b901-4f04edcb05a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_7f37a1cc-af62-4404-bef3-8030453557d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d3739cad-055f-4231-b901-4f04edcb05a6" xlink:to="loc_us-gaap_PlanNameAxis_7f37a1cc-af62-4404-bef3-8030453557d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_7f37a1cc-af62-4404-bef3-8030453557d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_7f37a1cc-af62-4404-bef3-8030453557d2" xlink:to="loc_us-gaap_PlanNameDomain_7f37a1cc-af62-4404-bef3-8030453557d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_97a7e404-7f07-46b1-81df-ec8da8e0ae4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_7f37a1cc-af62-4404-bef3-8030453557d2" xlink:to="loc_us-gaap_PlanNameDomain_97a7e404-7f07-46b1-81df-ec8da8e0ae4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NRGLTIPMember_262abadf-5c09-4d9d-b0bf-ba2e5247a372" xlink:href="nrg-20231231.xsd#nrg_NRGLTIPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_97a7e404-7f07-46b1-81df-ec8da8e0ae4c" xlink:to="loc_nrg_NRGLTIPMember_262abadf-5c09-4d9d-b0bf-ba2e5247a372" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_4c7e83d5-7f95-4017-ae6b-bc7a3386e5de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ff4c0dea-d112-4d78-8ddd-5f9c8ee2c65b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_4c7e83d5-7f95-4017-ae6b-bc7a3386e5de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_4edd81bc-36b7-4e77-b68f-1dd8cb28c69a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ff4c0dea-d112-4d78-8ddd-5f9c8ee2c65b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_4edd81bc-36b7-4e77-b68f-1dd8cb28c69a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationRestrictedStockUnitsRSUsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationRestrictedStockUnitsRSUsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationRestrictedStockUnitsRSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61221dff-eb0a-4fa8-93e4-8231394f656b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7ea98a52-bcc2-43f1-b6d9-1d7d3a654db3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61221dff-eb0a-4fa8-93e4-8231394f656b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7ea98a52-bcc2-43f1-b6d9-1d7d3a654db3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_772a0557-df17-47e9-bcbd-d1d5474dc279" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7ea98a52-bcc2-43f1-b6d9-1d7d3a654db3" xlink:to="loc_us-gaap_AwardTypeAxis_772a0557-df17-47e9-bcbd-d1d5474dc279" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_772a0557-df17-47e9-bcbd-d1d5474dc279_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_772a0557-df17-47e9-bcbd-d1d5474dc279" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_772a0557-df17-47e9-bcbd-d1d5474dc279_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_be6764c7-3b78-4508-bb81-37aeb7a7285d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_772a0557-df17-47e9-bcbd-d1d5474dc279" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_be6764c7-3b78-4508-bb81-37aeb7a7285d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_5f3e61a0-8d19-4bbf-88e8-0828cf989929" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_be6764c7-3b78-4508-bb81-37aeb7a7285d" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_5f3e61a0-8d19-4bbf-88e8-0828cf989929" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_92dc8b08-b7ad-4c22-ac5d-02c10bc67022" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61221dff-eb0a-4fa8-93e4-8231394f656b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_92dc8b08-b7ad-4c22-ac5d-02c10bc67022" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3817fefb-de74-426c-9c87-985ae1632c78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61221dff-eb0a-4fa8-93e4-8231394f656b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3817fefb-de74-426c-9c87-985ae1632c78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cb7f9a72-d484-45a8-9c79-535868e13b8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3817fefb-de74-426c-9c87-985ae1632c78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cb7f9a72-d484-45a8-9c79-535868e13b8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9cc9b313-3518-43ba-ac6a-0459cce36a39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3817fefb-de74-426c-9c87-985ae1632c78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_9cc9b313-3518-43ba-ac6a-0459cce36a39" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c644530f-f45b-45e4-bc5a-dcf6b60c7592" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3817fefb-de74-426c-9c87-985ae1632c78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c644530f-f45b-45e4-bc5a-dcf6b60c7592" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_8f58c17a-9fd8-4559-bcfb-3e5143a9292c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_3817fefb-de74-426c-9c87-985ae1632c78" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_8f58c17a-9fd8-4559-bcfb-3e5143a9292c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1887d8e2-f136-4edb-997f-79bf8548e584" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fab58c06-3121-44ad-b154-5dce47e54936" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61221dff-eb0a-4fa8-93e4-8231394f656b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fab58c06-3121-44ad-b154-5dce47e54936" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_bdf1471d-2ba8-4dab-b8b0-8fc72d5bd381" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fab58c06-3121-44ad-b154-5dce47e54936" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_bdf1471d-2ba8-4dab-b8b0-8fc72d5bd381" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_eca3d026-6c1b-4cbf-9fa9-bf0a8a0f7242" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fab58c06-3121-44ad-b154-5dce47e54936" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_eca3d026-6c1b-4cbf-9fa9-bf0a8a0f7242" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_a946d523-6ff7-4950-a1ae-c37f37a7e7c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fab58c06-3121-44ad-b154-5dce47e54936" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_a946d523-6ff7-4950-a1ae-c37f37a7e7c4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_aa76c14d-5e6a-4203-a49d-d14d76a22055" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_fab58c06-3121-44ad-b154-5dce47e54936" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_aa76c14d-5e6a-4203-a49d-d14d76a22055" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ab927714-23b9-4166-bb57-3ceffeda9c03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_9dfcc176-cf3a-4367-89e2-e5ec9339c652" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_61221dff-eb0a-4fa8-93e4-8231394f656b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_9dfcc176-cf3a-4367-89e2-e5ec9339c652" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_274f3fae-3313-41db-bc16-7e1e1149ea68" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationDeferredStockUnitsDSUsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationDeferredStockUnitsDSUsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationDeferredStockUnitsDSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c5d293d8-51de-487a-8d01-b853bd30056b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_49e7aad8-c156-4a3f-aba3-8e923622ac24" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c5d293d8-51de-487a-8d01-b853bd30056b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_49e7aad8-c156-4a3f-aba3-8e923622ac24" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_fc100676-2451-4e69-a9da-67a5c2590b73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_49e7aad8-c156-4a3f-aba3-8e923622ac24" xlink:to="loc_us-gaap_AwardTypeAxis_fc100676-2451-4e69-a9da-67a5c2590b73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fc100676-2451-4e69-a9da-67a5c2590b73_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_fc100676-2451-4e69-a9da-67a5c2590b73" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fc100676-2451-4e69-a9da-67a5c2590b73_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cca84729-0f1d-436a-acea-039e4d981787" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_fc100676-2451-4e69-a9da-67a5c2590b73" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cca84729-0f1d-436a-acea-039e4d981787" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DeferredStockUnitsMember_119294b9-4683-4e5e-a3cc-c3f1c061de2c" xlink:href="nrg-20231231.xsd#nrg_DeferredStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_cca84729-0f1d-436a-acea-039e4d981787" xlink:to="loc_nrg_DeferredStockUnitsMember_119294b9-4683-4e5e-a3cc-c3f1c061de2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRightToReceiveCommonStockAtEndOfDeferralPeriodShares_9a6aec6e-ec37-4a49-8958-8b1ecc2b0a35" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRightToReceiveCommonStockAtEndOfDeferralPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c5d293d8-51de-487a-8d01-b853bd30056b" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRightToReceiveCommonStockAtEndOfDeferralPeriodShares_9a6aec6e-ec37-4a49-8958-8b1ecc2b0a35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumberRollForward_dec5bbe0-cba6-4a4e-adfb-48bef240384b" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumberRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c5d293d8-51de-487a-8d01-b853bd30056b" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumberRollForward_dec5bbe0-cba6-4a4e-adfb-48bef240384b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumber_8ea68da2-437b-4465-a531-068e1b47bf43" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumberRollForward_dec5bbe0-cba6-4a4e-adfb-48bef240384b" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumber_8ea68da2-437b-4465-a531-068e1b47bf43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_6691afeb-ef8d-48e4-a565-067b4d5e1ad9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumberRollForward_dec5bbe0-cba6-4a4e-adfb-48bef240384b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_6691afeb-ef8d-48e4-a565-067b4d5e1ad9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_c1763054-bf4f-46be-873a-21b75bba4073" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumberRollForward_dec5bbe0-cba6-4a4e-adfb-48bef240384b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_c1763054-bf4f-46be-873a-21b75bba4073" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumber_b6b053a8-ed15-4511-ac34-b2edd7c31b7b" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsVestedWeightedAverageGrantDateFairValueAbstract_f5a0f933-af77-4846-b670-7f64e6ff2b52" xlink:href="nrg-20231231.xsd#nrg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsVestedWeightedAverageGrantDateFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c5d293d8-51de-487a-8d01-b853bd30056b" xlink:to="loc_nrg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsVestedWeightedAverageGrantDateFairValueAbstract_f5a0f933-af77-4846-b670-7f64e6ff2b52" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedWeightedAverageGrantDateFairValue_8c665b69-64c3-41ad-aeb2-fd5f1d3fb4e4" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsVestedWeightedAverageGrantDateFairValueAbstract_f5a0f933-af77-4846-b670-7f64e6ff2b52" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedWeightedAverageGrantDateFairValue_8c665b69-64c3-41ad-aeb2-fd5f1d3fb4e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_e26cbe67-fce4-4822-9c59-6e496695b4f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsVestedWeightedAverageGrantDateFairValueAbstract_f5a0f933-af77-4846-b670-7f64e6ff2b52" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_e26cbe67-fce4-4822-9c59-6e496695b4f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_66bbcd39-d2de-4c2e-85d3-451825b2462b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_nrg_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsVestedWeightedAverageGrantDateFairValueAbstract_f5a0f933-af77-4846-b670-7f64e6ff2b52" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_66bbcd39-d2de-4c2e-85d3-451825b2462b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedWeightedAverageGrantDateFairValue_7b0d6dd3-b1fd-469d-be03-9e4901eeae22" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAggregateIntrinsicValue_5ea11c6e-a4ba-464a-bc21-20555003e9d2" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c5d293d8-51de-487a-8d01-b853bd30056b" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAggregateIntrinsicValue_5ea11c6e-a4ba-464a-bc21-20555003e9d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsConversionsAggregateIntrinsicValue_1e0a3f46-c5de-4b90-afbd-58ccb8f4c8ca" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsConversionsAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c5d293d8-51de-487a-8d01-b853bd30056b" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsConversionsAggregateIntrinsicValue_1e0a3f46-c5de-4b90-afbd-58ccb8f4c8ca" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_0cdb91da-fb25-446b-ac0e-af8109c216f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationPerformanceStockUnitsRPSUsPlanDescriptionDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationPerformanceStockUnitsRPSUsPlanDescriptionDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationPerformanceStockUnitsRPSUsPlanDescriptionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fba5791-f229-4d76-9d46-33f9d4c1ecd7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_829089b5-70f8-4e9d-b92b-07fe41e9d957" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fba5791-f229-4d76-9d46-33f9d4c1ecd7" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_829089b5-70f8-4e9d-b92b-07fe41e9d957" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_ef2e9c62-4ed5-4cd4-8047-9b840ec5fa6b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_829089b5-70f8-4e9d-b92b-07fe41e9d957" xlink:to="loc_us-gaap_AwardTypeAxis_ef2e9c62-4ed5-4cd4-8047-9b840ec5fa6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ef2e9c62-4ed5-4cd4-8047-9b840ec5fa6b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_ef2e9c62-4ed5-4cd4-8047-9b840ec5fa6b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ef2e9c62-4ed5-4cd4-8047-9b840ec5fa6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb46b5dc-2995-4832-954b-fee15b32113b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_ef2e9c62-4ed5-4cd4-8047-9b840ec5fa6b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb46b5dc-2995-4832-954b-fee15b32113b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RelativePerformanceStockUnitsMember_e795e382-c879-4473-8ab0-e0bf8f7dfd94" xlink:href="nrg-20231231.xsd#nrg_RelativePerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_eb46b5dc-2995-4832-954b-fee15b32113b" xlink:to="loc_nrg_RelativePerformanceStockUnitsMember_e795e382-c879-4473-8ab0-e0bf8f7dfd94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_c1f33187-03e8-4303-b926-f9621ca2c3d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_829089b5-70f8-4e9d-b92b-07fe41e9d957" xlink:to="loc_us-gaap_VestingAxis_c1f33187-03e8-4303-b926-f9621ca2c3d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_c1f33187-03e8-4303-b926-f9621ca2c3d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_c1f33187-03e8-4303-b926-f9621ca2c3d9" xlink:to="loc_us-gaap_VestingDomain_c1f33187-03e8-4303-b926-f9621ca2c3d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_5d981bb7-7638-4453-98e6-13211513529b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_c1f33187-03e8-4303-b926-f9621ca2c3d9" xlink:to="loc_us-gaap_VestingDomain_5d981bb7-7638-4453-98e6-13211513529b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_7033bf2f-3a2f-453b-86a5-192da842d5bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_5d981bb7-7638-4453-98e6-13211513529b" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_7033bf2f-3a2f-453b-86a5-192da842d5bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_b76e04bc-f0bc-436f-85b5-97b15f02b986" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_5d981bb7-7638-4453-98e6-13211513529b" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_b76e04bc-f0bc-436f-85b5-97b15f02b986" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_aec93611-8532-4099-ab67-e2da36973ef9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_5d981bb7-7638-4453-98e6-13211513529b" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_aec93611-8532-4099-ab67-e2da36973ef9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedPaymentArrangementTrancheFourMember_4d7c814e-7282-462d-95a2-70d75540d330" xlink:href="nrg-20231231.xsd#nrg_ShareBasedPaymentArrangementTrancheFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_5d981bb7-7638-4453-98e6-13211513529b" xlink:to="loc_nrg_ShareBasedPaymentArrangementTrancheFourMember_4d7c814e-7282-462d-95a2-70d75540d330" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedPaymentArrangementTrancheFiveMember_8af434ba-f7ec-455d-90a7-c34e08b4ac81" xlink:href="nrg-20231231.xsd#nrg_ShareBasedPaymentArrangementTrancheFiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_5d981bb7-7638-4453-98e6-13211513529b" xlink:to="loc_nrg_ShareBasedPaymentArrangementTrancheFiveMember_8af434ba-f7ec-455d-90a7-c34e08b4ac81" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_bee69ea7-e178-4941-b87f-06e03b8e004a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fba5791-f229-4d76-9d46-33f9d4c1ecd7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_bee69ea7-e178-4941-b87f-06e03b8e004a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_bfc6b51e-004b-44a1-974a-133f7b08c1d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_9fba5791-f229-4d76-9d46-33f9d4c1ecd7" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_bfc6b51e-004b-44a1-974a-133f7b08c1d2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationRelativePerformanceStockUnitsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationRelativePerformanceStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationRelativePerformanceStockUnitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c845006-5a02-46c5-a4c8-db6df1e0cda9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62fec90b-61d9-4b37-9fa1-e2a7535f9032" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c845006-5a02-46c5-a4c8-db6df1e0cda9" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62fec90b-61d9-4b37-9fa1-e2a7535f9032" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_0fadb757-647b-404d-95d2-a32073293b2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_62fec90b-61d9-4b37-9fa1-e2a7535f9032" xlink:to="loc_us-gaap_AwardTypeAxis_0fadb757-647b-404d-95d2-a32073293b2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0fadb757-647b-404d-95d2-a32073293b2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0fadb757-647b-404d-95d2-a32073293b2d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0fadb757-647b-404d-95d2-a32073293b2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_def6d06e-a910-4342-87e0-05665930c2e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0fadb757-647b-404d-95d2-a32073293b2d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_def6d06e-a910-4342-87e0-05665930c2e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RelativePerformanceStockUnitsMember_2271b606-a55d-4da3-a3da-895e7b2893bf" xlink:href="nrg-20231231.xsd#nrg_RelativePerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_def6d06e-a910-4342-87e0-05665930c2e3" xlink:to="loc_nrg_RelativePerformanceStockUnitsMember_2271b606-a55d-4da3-a3da-895e7b2893bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3e2fd9a-78e2-4b1d-827d-ee68e2121bcc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c845006-5a02-46c5-a4c8-db6df1e0cda9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3e2fd9a-78e2-4b1d-827d-ee68e2121bcc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_67ea1748-45af-409e-86ac-8f079bed66c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3e2fd9a-78e2-4b1d-827d-ee68e2121bcc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_67ea1748-45af-409e-86ac-8f079bed66c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_b149bc67-2dea-4c7e-9e84-615345f4d56e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3e2fd9a-78e2-4b1d-827d-ee68e2121bcc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_b149bc67-2dea-4c7e-9e84-615345f4d56e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_2829a317-d6fb-486b-90a1-346b021fac39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3e2fd9a-78e2-4b1d-827d-ee68e2121bcc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_2829a317-d6fb-486b-90a1-346b021fac39" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_b8db2f86-e776-46a0-b68f-c9efdbe30ad3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_e3e2fd9a-78e2-4b1d-827d-ee68e2121bcc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_b8db2f86-e776-46a0-b68f-c9efdbe30ad3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_e7441046-c6f7-4a87-880c-e731a7c3052b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_08e03e69-f054-40a3-a925-f023219b74b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c845006-5a02-46c5-a4c8-db6df1e0cda9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_08e03e69-f054-40a3-a925-f023219b74b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_fa109478-29a4-4616-a0ab-81fd4ca55fc6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_08e03e69-f054-40a3-a925-f023219b74b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_fa109478-29a4-4616-a0ab-81fd4ca55fc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_215911f8-2d5b-4791-8add-a2e6718ce678" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_08e03e69-f054-40a3-a925-f023219b74b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_215911f8-2d5b-4791-8add-a2e6718ce678" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_0acd904e-e2ed-4a3c-82da-e9a94191d9e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_08e03e69-f054-40a3-a925-f023219b74b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_0acd904e-e2ed-4a3c-82da-e9a94191d9e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_e4d376fa-0c91-4b33-b4f0-a8c45d832805" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_08e03e69-f054-40a3-a925-f023219b74b8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_e4d376fa-0c91-4b33-b4f0-a8c45d832805" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_2567a49d-7e67-43f8-9252-b0f811972d37" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPayoutPercentage_1c9bdc2f-54a6-4d86-b26a-6538385fdd4d" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPayoutPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c845006-5a02-46c5-a4c8-db6df1e0cda9" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingPayoutPercentage_1c9bdc2f-54a6-4d86-b26a-6538385fdd4d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_809c11b1-e751-4671-8b94-e6a9ae9f37bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_7c845006-5a02-46c5-a4c8-db6df1e0cda9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_809c11b1-e751-4671-8b94-e6a9ae9f37bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_8e8fd2b0-8ee7-42b7-8471-b9a34a3dfe6f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_809c11b1-e751-4671-8b94-e6a9ae9f37bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_8e8fd2b0-8ee7-42b7-8471-b9a34a3dfe6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_3026b935-e74c-4af1-9bfd-1617dd4665dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_809c11b1-e751-4671-8b94-e6a9ae9f37bc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_3026b935-e74c-4af1-9bfd-1617dd4665dd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_c83f1759-a238-4ab6-b61e-8b576996cebe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_809c11b1-e751-4671-8b94-e6a9ae9f37bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_c83f1759-a238-4ab6-b61e-8b576996cebe" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationVivintLongTermIncentivePlanNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationVivintLongTermIncentivePlanNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationVivintLongTermIncentivePlanNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_391af231-3f16-4b2c-ab6b-53a193f7d9ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27cd267f-4c66-4220-9b79-fa20495deb51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_391af231-3f16-4b2c-ab6b-53a193f7d9ce" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27cd267f-4c66-4220-9b79-fa20495deb51" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_8bec0e35-d100-4618-ada1-088999c6873a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27cd267f-4c66-4220-9b79-fa20495deb51" xlink:to="loc_us-gaap_AwardTypeAxis_8bec0e35-d100-4618-ada1-088999c6873a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8bec0e35-d100-4618-ada1-088999c6873a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_8bec0e35-d100-4618-ada1-088999c6873a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_8bec0e35-d100-4618-ada1-088999c6873a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_23df9602-5f29-4292-ab6e-535c1092a744" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_8bec0e35-d100-4618-ada1-088999c6873a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_23df9602-5f29-4292-ab6e-535c1092a744" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_6f0e9764-3494-4e1a-9dac-cdcb9d625104" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_23df9602-5f29-4292-ab6e-535c1092a744" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_6f0e9764-3494-4e1a-9dac-cdcb9d625104" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_04aea6b6-9cc7-4d98-ad2a-6b49cbb36113" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_27cd267f-4c66-4220-9b79-fa20495deb51" xlink:to="loc_us-gaap_PlanNameAxis_04aea6b6-9cc7-4d98-ad2a-6b49cbb36113" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_04aea6b6-9cc7-4d98-ad2a-6b49cbb36113_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_04aea6b6-9cc7-4d98-ad2a-6b49cbb36113" xlink:to="loc_us-gaap_PlanNameDomain_04aea6b6-9cc7-4d98-ad2a-6b49cbb36113_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_3a8cff37-b769-42a8-b989-9c2329e2334d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_04aea6b6-9cc7-4d98-ad2a-6b49cbb36113" xlink:to="loc_us-gaap_PlanNameDomain_3a8cff37-b769-42a8-b989-9c2329e2334d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintLTIPMember_b6d2254f-9381-4158-85dd-7a8ed1dc8e00" xlink:href="nrg-20231231.xsd#nrg_VivintLTIPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_3a8cff37-b769-42a8-b989-9c2329e2334d" xlink:to="loc_nrg_VivintLTIPMember_b6d2254f-9381-4158-85dd-7a8ed1dc8e00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_c5ee5f74-cce3-45d1-a09a-1f78e65d1f37" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_391af231-3f16-4b2c-ab6b-53a193f7d9ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_c5ee5f74-cce3-45d1-a09a-1f78e65d1f37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_a4b708dd-65c7-450b-9b5a-dd87dd011b36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_391af231-3f16-4b2c-ab6b-53a193f7d9ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_a4b708dd-65c7-450b-9b5a-dd87dd011b36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e022aab7-2e65-414a-8890-eb79ccc18841" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_391af231-3f16-4b2c-ab6b-53a193f7d9ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e022aab7-2e65-414a-8890-eb79ccc18841" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationSummaryofVivintRSUsDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationSummaryofVivintRSUsDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationSummaryofVivintRSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d6ded8ae-b9ce-42c3-92a7-6d1dbcd8d72a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0476fd52-cc6d-4256-a11e-d7e56763c5e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d6ded8ae-b9ce-42c3-92a7-6d1dbcd8d72a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0476fd52-cc6d-4256-a11e-d7e56763c5e1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_b72f7ead-af77-4375-b145-c3727a1834ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0476fd52-cc6d-4256-a11e-d7e56763c5e1" xlink:to="loc_us-gaap_AwardTypeAxis_b72f7ead-af77-4375-b145-c3727a1834ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b72f7ead-af77-4375-b145-c3727a1834ee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_b72f7ead-af77-4375-b145-c3727a1834ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_b72f7ead-af77-4375-b145-c3727a1834ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_053f70ec-16b8-4639-991b-e362d12dc356" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_b72f7ead-af77-4375-b145-c3727a1834ee" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_053f70ec-16b8-4639-991b-e362d12dc356" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RolloverRestrictedStockUnitsRSUMember_51a800e5-d898-44dd-b498-e3919de128e9" xlink:href="nrg-20231231.xsd#nrg_RolloverRestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_053f70ec-16b8-4639-991b-e362d12dc356" xlink:to="loc_nrg_RolloverRestrictedStockUnitsRSUMember_51a800e5-d898-44dd-b498-e3919de128e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RestrictedStockUnitsPostAcquisitionMember_89b51c87-33f6-4f32-8921-f3d7fed40b49" xlink:href="nrg-20231231.xsd#nrg_RestrictedStockUnitsPostAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_053f70ec-16b8-4639-991b-e362d12dc356" xlink:to="loc_nrg_RestrictedStockUnitsPostAcquisitionMember_89b51c87-33f6-4f32-8921-f3d7fed40b49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_e26c09c4-aff2-4a11-a05a-08775155583f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_053f70ec-16b8-4639-991b-e362d12dc356" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_e26c09c4-aff2-4a11-a05a-08775155583f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_46fb9a98-997b-4a3b-a901-daedda3beb67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_0476fd52-cc6d-4256-a11e-d7e56763c5e1" xlink:to="loc_us-gaap_PlanNameAxis_46fb9a98-997b-4a3b-a901-daedda3beb67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_46fb9a98-997b-4a3b-a901-daedda3beb67_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_46fb9a98-997b-4a3b-a901-daedda3beb67" xlink:to="loc_us-gaap_PlanNameDomain_46fb9a98-997b-4a3b-a901-daedda3beb67_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_e56128bf-d660-4900-8af0-8798b5c2229d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_46fb9a98-997b-4a3b-a901-daedda3beb67" xlink:to="loc_us-gaap_PlanNameDomain_e56128bf-d660-4900-8af0-8798b5c2229d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintLTIPMember_beeb215d-fad4-45f1-990d-90c3479c9d4c" xlink:href="nrg-20231231.xsd#nrg_VivintLTIPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_e56128bf-d660-4900-8af0-8798b5c2229d" xlink:to="loc_nrg_VivintLTIPMember_beeb215d-fad4-45f1-990d-90c3479c9d4c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f5ca8e32-882e-4b74-8007-006ca580eea2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d6ded8ae-b9ce-42c3-92a7-6d1dbcd8d72a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f5ca8e32-882e-4b74-8007-006ca580eea2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2b9a4e0b-563b-4bb2-b1aa-7f542d68731d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f5ca8e32-882e-4b74-8007-006ca580eea2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2b9a4e0b-563b-4bb2-b1aa-7f542d68731d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollOverNumberAcquisitionDate_dfe1264c-db48-4d2f-be7a-dd2e4dfaf7ac" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollOverNumberAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f5ca8e32-882e-4b74-8007-006ca580eea2" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollOverNumberAcquisitionDate_dfe1264c-db48-4d2f-be7a-dd2e4dfaf7ac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_fcd6d88c-fc40-4c6e-937e-369a204615a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f5ca8e32-882e-4b74-8007-006ca580eea2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_fcd6d88c-fc40-4c6e-937e-369a204615a6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_fe016a71-eb30-4ae0-9eec-4508cddb3d03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f5ca8e32-882e-4b74-8007-006ca580eea2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_fe016a71-eb30-4ae0-9eec-4508cddb3d03" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_93368292-93ad-4c5c-ab56-fa89abb7e727" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_f5ca8e32-882e-4b74-8007-006ca580eea2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_93368292-93ad-4c5c-ab56-fa89abb7e727" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_8ce4145d-b223-489f-a5b4-be0a31776b87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b609006-c56f-4ebf-a823-c8b4201e9a04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d6ded8ae-b9ce-42c3-92a7-6d1dbcd8d72a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b609006-c56f-4ebf-a823-c8b4201e9a04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_71a4a057-557c-4234-b28d-079b87cb7db1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b609006-c56f-4ebf-a823-c8b4201e9a04" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_71a4a057-557c-4234-b28d-079b87cb7db1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedAcquisitionDateWeightedAverageGrantDateFairValue_18bf7be7-19e4-4d22-a444-3ed8d7d21584" xlink:href="nrg-20231231.xsd#nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedAcquisitionDateWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b609006-c56f-4ebf-a823-c8b4201e9a04" xlink:to="loc_nrg_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedAcquisitionDateWeightedAverageGrantDateFairValue_18bf7be7-19e4-4d22-a444-3ed8d7d21584" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_bf0c9598-b632-40aa-859b-fccf11cfdce5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b609006-c56f-4ebf-a823-c8b4201e9a04" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_bf0c9598-b632-40aa-859b-fccf11cfdce5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_a46b9821-ff16-4c21-88ec-0383c1f5b7dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b609006-c56f-4ebf-a823-c8b4201e9a04" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_a46b9821-ff16-4c21-88ec-0383c1f5b7dc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_12655064-2c2e-46e2-85a9-178e95568f1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b609006-c56f-4ebf-a823-c8b4201e9a04" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_12655064-2c2e-46e2-85a9-178e95568f1f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_a7436af7-45a5-4b2b-a8c6-48609a600b84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_21990b40-2fb9-4dad-80ce-d9e84978020e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d6ded8ae-b9ce-42c3-92a7-6d1dbcd8d72a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_21990b40-2fb9-4dad-80ce-d9e84978020e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationPSUsGrantedUnderVivintLTIPDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationPSUsGrantedUnderVivintLTIPDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationPSUsGrantedUnderVivintLTIPDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8c62dd14-dc13-4606-ad49-0cb53b250a32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6c03bb60-2442-466a-8621-64464b0d8a02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8c62dd14-dc13-4606-ad49-0cb53b250a32" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6c03bb60-2442-466a-8621-64464b0d8a02" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_70f0680a-29ab-4838-ba2a-e05d4e87b595" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6c03bb60-2442-466a-8621-64464b0d8a02" xlink:to="loc_us-gaap_AwardTypeAxis_70f0680a-29ab-4838-ba2a-e05d4e87b595" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_70f0680a-29ab-4838-ba2a-e05d4e87b595_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_70f0680a-29ab-4838-ba2a-e05d4e87b595" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_70f0680a-29ab-4838-ba2a-e05d4e87b595_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0cb9bfe3-f32c-48e5-896e-7bcfb58d5940" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_70f0680a-29ab-4838-ba2a-e05d4e87b595" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0cb9bfe3-f32c-48e5-896e-7bcfb58d5940" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_d7106c7a-a3f5-4fba-b360-fd82de41c98e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0cb9bfe3-f32c-48e5-896e-7bcfb58d5940" xlink:to="loc_us-gaap_PerformanceSharesMember_d7106c7a-a3f5-4fba-b360-fd82de41c98e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_115e2c4d-d0e5-4f8d-a20c-912017fc33dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6c03bb60-2442-466a-8621-64464b0d8a02" xlink:to="loc_us-gaap_PlanNameAxis_115e2c4d-d0e5-4f8d-a20c-912017fc33dc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_115e2c4d-d0e5-4f8d-a20c-912017fc33dc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_115e2c4d-d0e5-4f8d-a20c-912017fc33dc" xlink:to="loc_us-gaap_PlanNameDomain_115e2c4d-d0e5-4f8d-a20c-912017fc33dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_dd99a3dd-5309-407d-ab69-63def3c5755a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_115e2c4d-d0e5-4f8d-a20c-912017fc33dc" xlink:to="loc_us-gaap_PlanNameDomain_dd99a3dd-5309-407d-ab69-63def3c5755a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintLTIPMember_c130bda7-2f00-4d62-a6d8-538ee1b2a442" xlink:href="nrg-20231231.xsd#nrg_VivintLTIPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_dd99a3dd-5309-407d-ab69-63def3c5755a" xlink:to="loc_nrg_VivintLTIPMember_c130bda7-2f00-4d62-a6d8-538ee1b2a442" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_2f9f27ab-90fe-4bae-ae0e-c180088cf332" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8c62dd14-dc13-4606-ad49-0cb53b250a32" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_2f9f27ab-90fe-4bae-ae0e-c180088cf332" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_925c0776-9efb-436a-bc48-86b603c0ce5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8c62dd14-dc13-4606-ad49-0cb53b250a32" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_925c0776-9efb-436a-bc48-86b603c0ce5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_3d576c2d-f530-4c59-a592-24b068bb0241" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8c62dd14-dc13-4606-ad49-0cb53b250a32" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_3d576c2d-f530-4c59-a592-24b068bb0241" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7bf93330-1cdd-412e-8998-b200611c324a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8c62dd14-dc13-4606-ad49-0cb53b250a32" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_7bf93330-1cdd-412e-8998-b200611c324a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/StockBasedCompensationSupplementalInformationDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#StockBasedCompensationSupplementalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/StockBasedCompensationSupplementalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_61b8c4c5-2057-4d16-b0a3-45351a80849e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_61b8c4c5-2057-4d16-b0a3-45351a80849e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_401506c1-903b-49d9-b407-03e54073bb01" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_61b8c4c5-2057-4d16-b0a3-45351a80849e" xlink:to="loc_us-gaap_AwardTypeAxis_401506c1-903b-49d9-b407-03e54073bb01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_401506c1-903b-49d9-b407-03e54073bb01_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_401506c1-903b-49d9-b407-03e54073bb01" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_401506c1-903b-49d9-b407-03e54073bb01_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_837cba3e-a146-4013-8104-183e764d49fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_401506c1-903b-49d9-b407-03e54073bb01" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_837cba3e-a146-4013-8104-183e764d49fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_9f0d8a81-a232-4bca-b0ec-b41c189351cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_837cba3e-a146-4013-8104-183e764d49fe" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_9f0d8a81-a232-4bca-b0ec-b41c189351cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_a009fc98-7a29-40ec-bb1a-ad1ecbaa341d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_837cba3e-a146-4013-8104-183e764d49fe" xlink:to="loc_us-gaap_PerformanceSharesMember_a009fc98-7a29-40ec-bb1a-ad1ecbaa341d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DeferredStockUnitsMember_1d0f540d-1812-4d86-b148-03f042d6447e" xlink:href="nrg-20231231.xsd#nrg_DeferredStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_837cba3e-a146-4013-8104-183e764d49fe" xlink:to="loc_nrg_DeferredStockUnitsMember_1d0f540d-1812-4d86-b148-03f042d6447e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RelativePerformanceStockUnitsMember_a7e5edfe-1434-4414-96ae-69f780ba76a8" xlink:href="nrg-20231231.xsd#nrg_RelativePerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_837cba3e-a146-4013-8104-183e764d49fe" xlink:to="loc_nrg_RelativePerformanceStockUnitsMember_a7e5edfe-1434-4414-96ae-69f780ba76a8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PhantomRestrictedStockUnitsPRSUsMember_dec08b7a-99fe-4aa1-9cad-a678e3edeb85" xlink:href="nrg-20231231.xsd#nrg_PhantomRestrictedStockUnitsPRSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_837cba3e-a146-4013-8104-183e764d49fe" xlink:to="loc_nrg_PhantomRestrictedStockUnitsPRSUsMember_dec08b7a-99fe-4aa1-9cad-a678e3edeb85" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_96e43522-6907-4537-bd3c-873137fc6fe7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_61b8c4c5-2057-4d16-b0a3-45351a80849e" xlink:to="loc_us-gaap_PlanNameAxis_96e43522-6907-4537-bd3c-873137fc6fe7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_96e43522-6907-4537-bd3c-873137fc6fe7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_96e43522-6907-4537-bd3c-873137fc6fe7" xlink:to="loc_us-gaap_PlanNameDomain_96e43522-6907-4537-bd3c-873137fc6fe7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_9888e05d-0348-45e2-89b3-d479227112bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_96e43522-6907-4537-bd3c-873137fc6fe7" xlink:to="loc_us-gaap_PlanNameDomain_9888e05d-0348-45e2-89b3-d479227112bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintLTIPMember_845c45e4-c66a-4b18-a9ca-1133fc48551e" xlink:href="nrg-20231231.xsd#nrg_VivintLTIPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_9888e05d-0348-45e2-89b3-d479227112bf" xlink:to="loc_nrg_VivintLTIPMember_845c45e4-c66a-4b18-a9ca-1133fc48551e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LongTermIncentivePlanMember_fc599dec-c669-44d6-b62e-42e03215981f" xlink:href="nrg-20231231.xsd#nrg_LongTermIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_9888e05d-0348-45e2-89b3-d479227112bf" xlink:to="loc_nrg_LongTermIncentivePlanMember_fc599dec-c669-44d6-b62e-42e03215981f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_dc55c97b-639e-49b8-ac60-a05442ddd26b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_dc55c97b-639e-49b8-ac60-a05442ddd26b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_aa93b2cf-9f51-4cf4-aad9-658f432635ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_aa93b2cf-9f51-4cf4-aad9-658f432635ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_b950c03f-ed07-4866-86b0-1d8bb9b6d882" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_b950c03f-ed07-4866-86b0-1d8bb9b6d882" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_b9f8bc84-7dfc-4972-82f8-5daa95a647df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_b9f8bc84-7dfc-4972-82f8-5daa95a647df" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b8513774-6e4a-45da-92be-4afdc1382549" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b8513774-6e4a-45da-92be-4afdc1382549" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_c0102431-1323-4ac5-8d74-8d44e4e6888a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_308323d6-0098-46ba-bcec-8809f6b4a81d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_c0102431-1323-4ac5-8d74-8d44e4e6888a" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RelatedPartyTransactionsSummaryofMaterialRelatedPartyTransactionswithThirdPartyAffiliatesDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#RelatedPartyTransactionsSummaryofMaterialRelatedPartyTransactionswithThirdPartyAffiliatesDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RelatedPartyTransactionsSummaryofMaterialRelatedPartyTransactionswithThirdPartyAffiliatesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_701eea16-fc4f-4ed4-87c8-7e9292203f7c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a64db1c-69ea-43e6-8c6c-eece726589df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_701eea16-fc4f-4ed4-87c8-7e9292203f7c" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a64db1c-69ea-43e6-8c6c-eece726589df" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d2fac1b0-43b6-4a38-ba23-9e3c7d10f247" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a64db1c-69ea-43e6-8c6c-eece726589df" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d2fac1b0-43b6-4a38-ba23-9e3c7d10f247" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_d2fac1b0-43b6-4a38-ba23-9e3c7d10f247_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d2fac1b0-43b6-4a38-ba23-9e3c7d10f247" xlink:to="loc_us-gaap_RelatedPartyDomain_d2fac1b0-43b6-4a38-ba23-9e3c7d10f247_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_bbd19c2f-c534-47d7-8529-d5c8cb064e64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d2fac1b0-43b6-4a38-ba23-9e3c7d10f247" xlink:to="loc_us-gaap_RelatedPartyDomain_bbd19c2f-c534-47d7-8529-d5c8cb064e64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_675e717d-4020-4389-be39-212bf1268899" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_bbd19c2f-c534-47d7-8529-d5c8cb064e64" xlink:to="loc_us-gaap_RelatedPartyMember_675e717d-4020-4389-be39-212bf1268899" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_c7166cf7-ab12-46f0-a431-e99053fd011a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_7a64db1c-69ea-43e6-8c6c-eece726589df" xlink:to="loc_srt_CounterpartyNameAxis_c7166cf7-ab12-46f0-a431-e99053fd011a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c7166cf7-ab12-46f0-a431-e99053fd011a_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_c7166cf7-ab12-46f0-a431-e99053fd011a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_c7166cf7-ab12-46f0-a431-e99053fd011a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6f66b45c-69df-493c-a4a5-c78a82e83bf3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_c7166cf7-ab12-46f0-a431-e99053fd011a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6f66b45c-69df-493c-a4a5-c78a82e83bf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GladstonePowerStationMember_6e981629-6d33-4935-be7a-0d7ac912333f" xlink:href="nrg-20231231.xsd#nrg_GladstonePowerStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6f66b45c-69df-493c-a4a5-c78a82e83bf3" xlink:to="loc_nrg_GladstonePowerStationMember_6e981629-6d33-4935-be7a-0d7ac912333f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_IvanpahMember_068e32bc-4b6d-4015-a58c-33c1b3030efb" xlink:href="nrg-20231231.xsd#nrg_IvanpahMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6f66b45c-69df-493c-a4a5-c78a82e83bf3" xlink:to="loc_nrg_IvanpahMember_068e32bc-4b6d-4015-a58c-33c1b3030efb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_MidwaySunsetCogenerationCompanyMember_8438a535-7600-4b56-8bed-abcfc6566770" xlink:href="nrg-20231231.xsd#nrg_MidwaySunsetCogenerationCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_6f66b45c-69df-493c-a4a5-c78a82e83bf3" xlink:to="loc_nrg_MidwaySunsetCogenerationCompanyMember_8438a535-7600-4b56-8bed-abcfc6566770" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_43847868-f163-4349-bce3-972543b211d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_701eea16-fc4f-4ed4-87c8-7e9292203f7c" xlink:to="loc_us-gaap_Revenues_43847868-f163-4349-bce3-972543b211d1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#CommitmentsandContingenciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_55098935-1bbc-4cc6-a21d-8cfd0a380f90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_9f3a5530-643a-4531-b680-ad634390e8ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_55098935-1bbc-4cc6-a21d-8cfd0a380f90" xlink:to="loc_us-gaap_LossContingenciesTable_9f3a5530-643a-4531-b680-ad634390e8ec" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_3d05e2a1-9bc7-4913-8a24-1aa5ecbf4d00" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_9f3a5530-643a-4531-b680-ad634390e8ec" xlink:to="loc_srt_LitigationCaseAxis_3d05e2a1-9bc7-4913-8a24-1aa5ecbf4d00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_3d05e2a1-9bc7-4913-8a24-1aa5ecbf4d00_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_3d05e2a1-9bc7-4913-8a24-1aa5ecbf4d00" xlink:to="loc_srt_LitigationCaseTypeDomain_3d05e2a1-9bc7-4913-8a24-1aa5ecbf4d00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_3d05e2a1-9bc7-4913-8a24-1aa5ecbf4d00" xlink:to="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SierraClubEtAlVMidwestGenerationLLCMember_dabce55b-c190-4ced-8950-675d2acb7461" xlink:href="nrg-20231231.xsd#nrg_SierraClubEtAlVMidwestGenerationLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:to="loc_nrg_SierraClubEtAlVMidwestGenerationLLCMember_dabce55b-c190-4ced-8950-675d2acb7461" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DirectEnergyVsStanleyForteSchaferAndLaneMember_cfc8768d-4e4e-4354-9984-956944b88824" xlink:href="nrg-20231231.xsd#nrg_DirectEnergyVsStanleyForteSchaferAndLaneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:to="loc_nrg_DirectEnergyVsStanleyForteSchaferAndLaneMember_cfc8768d-4e4e-4354-9984-956944b88824" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DirectEnergyVsBurkAndDicksonLitigationMember_3f4ce07c-a06d-4eb7-92e1-662ddaafb1f7" xlink:href="nrg-20231231.xsd#nrg_DirectEnergyVsBurkAndDicksonLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:to="loc_nrg_DirectEnergyVsBurkAndDicksonLitigationMember_3f4ce07c-a06d-4eb7-92e1-662ddaafb1f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CPISecuritySystemsIncMember_db912da1-72ba-49fa-9b63-4862b3155255" xlink:href="nrg-20231231.xsd#nrg_CPISecuritySystemsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:to="loc_nrg_CPISecuritySystemsIncMember_db912da1-72ba-49fa-9b63-4862b3155255" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SBIPHoldingsLLCSkybellVVivintSmartHomeIncMember_e45e8b69-1ed6-401e-88c3-9eb6b0ad9a27" xlink:href="nrg-20231231.xsd#nrg_SBIPHoldingsLLCSkybellVVivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:to="loc_nrg_SBIPHoldingsLLCSkybellVVivintSmartHomeIncMember_e45e8b69-1ed6-401e-88c3-9eb6b0ad9a27" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PartnersInSTPCPSAndAustinEnergyVsNRGMember_61e40178-3a9c-4cb3-9158-6098c4d9a25b" xlink:href="nrg-20231231.xsd#nrg_PartnersInSTPCPSAndAustinEnergyVsNRGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_dc4e0f93-6d78-47fc-b8cc-0e834d97a025" xlink:to="loc_nrg_PartnersInSTPCPSAndAustinEnergyVsNRGMember_61e40178-3a9c-4cb3-9158-6098c4d9a25b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_81813b8b-9f48-4079-8e05-20a03c6f3df7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_9f3a5530-643a-4531-b680-ad634390e8ec" xlink:to="loc_us-gaap_LitigationStatusAxis_81813b8b-9f48-4079-8e05-20a03c6f3df7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_81813b8b-9f48-4079-8e05-20a03c6f3df7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_81813b8b-9f48-4079-8e05-20a03c6f3df7" xlink:to="loc_us-gaap_LitigationStatusDomain_81813b8b-9f48-4079-8e05-20a03c6f3df7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_da02c36a-6f2b-4f01-9a3e-a548232e6d3a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_81813b8b-9f48-4079-8e05-20a03c6f3df7" xlink:to="loc_us-gaap_LitigationStatusDomain_da02c36a-6f2b-4f01-9a3e-a548232e6d3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_ed5ea01a-7469-429f-a96f-7c410bf27103" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_da02c36a-6f2b-4f01-9a3e-a548232e6d3a" xlink:to="loc_us-gaap_PendingLitigationMember_ed5ea01a-7469-429f-a96f-7c410bf27103" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a322d3da-fe59-4d9c-93bf-8f388b001aec" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_9f3a5530-643a-4531-b680-ad634390e8ec" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a322d3da-fe59-4d9c-93bf-8f388b001aec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_a322d3da-fe59-4d9c-93bf-8f388b001aec_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a322d3da-fe59-4d9c-93bf-8f388b001aec" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_a322d3da-fe59-4d9c-93bf-8f388b001aec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_ae950d84-e70e-420c-845e-8f44cd62bd4a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_a322d3da-fe59-4d9c-93bf-8f388b001aec" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_ae950d84-e70e-420c-845e-8f44cd62bd4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_d52edb06-4258-4a27-a096-3932e17439b4" xlink:href="nrg-20231231.xsd#nrg_SouthTexasProjectElectricGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_ae950d84-e70e-420c-845e-8f44cd62bd4a" xlink:to="loc_nrg_SouthTexasProjectElectricGeneratingStationMember_d52edb06-4258-4a27-a096-3932e17439b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfFacilities_b569b29e-4c27-4250-a960-0413edcbd892" xlink:href="nrg-20231231.xsd#nrg_NumberOfFacilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_55098935-1bbc-4cc6-a21d-8cfd0a380f90" xlink:to="loc_nrg_NumberOfFacilities_b569b29e-4c27-4250-a960-0413edcbd892" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_d9b283d3-8f83-477a-adf5-921b833d0a1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_55098935-1bbc-4cc6-a21d-8cfd0a380f90" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_d9b283d3-8f83-477a-adf5-921b833d0a1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_db17e65f-dcb1-4e5f-a7d0-7354543dc0e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyDamagesAwardedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_55098935-1bbc-4cc6-a21d-8cfd0a380f90" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_db17e65f-dcb1-4e5f-a7d0-7354543dc0e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LossContingencyPunitiveDamagesAwardedValue_7c6df741-0557-4c7a-a96d-462aec9ced94" xlink:href="nrg-20231231.xsd#nrg_LossContingencyPunitiveDamagesAwardedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_55098935-1bbc-4cc6-a21d-8cfd0a380f90" xlink:to="loc_nrg_LossContingencyPunitiveDamagesAwardedValue_7c6df741-0557-4c7a-a96d-462aec9ced94" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_ca2e740f-6b7b-48a7-80a3-aa03dba1defa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_55098935-1bbc-4cc6-a21d-8cfd0a380f90" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_ca2e740f-6b7b-48a7-80a3-aa03dba1defa" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/RegulatoryMattersDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#RegulatoryMattersDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/RegulatoryMattersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_65b17b85-2400-4ee4-9857-5a443c6a5177" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_b32668e6-e94e-4bb5-b2ad-592b65bc11f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_65b17b85-2400-4ee4-9857-5a443c6a5177" xlink:to="loc_us-gaap_LossContingenciesTable_b32668e6-e94e-4bb5-b2ad-592b65bc11f2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_2c8d7140-2c05-4b92-9ce2-b62f548119aa" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_b32668e6-e94e-4bb5-b2ad-592b65bc11f2" xlink:to="loc_dei_LegalEntityAxis_2c8d7140-2c05-4b92-9ce2-b62f548119aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_2c8d7140-2c05-4b92-9ce2-b62f548119aa_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_2c8d7140-2c05-4b92-9ce2-b62f548119aa" xlink:to="loc_dei_EntityDomain_2c8d7140-2c05-4b92-9ce2-b62f548119aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_9259fd3e-1b3e-4ee6-a11e-b8a97b58b879" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_2c8d7140-2c05-4b92-9ce2-b62f548119aa" xlink:to="loc_dei_EntityDomain_9259fd3e-1b3e-4ee6-a11e-b8a97b58b879" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_VivintSmartHomeIncMember_0bcd9aed-15ca-4c8c-a191-28c47c8d206d" xlink:href="nrg-20231231.xsd#nrg_VivintSmartHomeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_9259fd3e-1b3e-4ee6-a11e-b8a97b58b879" xlink:to="loc_nrg_VivintSmartHomeIncMember_0bcd9aed-15ca-4c8c-a191-28c47c8d206d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_00d692f8-fc3e-4dab-afee-4dfcd1d6ea23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_b32668e6-e94e-4bb5-b2ad-592b65bc11f2" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_00d692f8-fc3e-4dab-afee-4dfcd1d6ea23" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_00d692f8-fc3e-4dab-afee-4dfcd1d6ea23_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_00d692f8-fc3e-4dab-afee-4dfcd1d6ea23" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_00d692f8-fc3e-4dab-afee-4dfcd1d6ea23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ae5f34e8-0986-44f1-8ea9-b6df3c9faa71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_00d692f8-fc3e-4dab-afee-4dfcd1d6ea23" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ae5f34e8-0986-44f1-8ea9-b6df3c9faa71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_7fc64937-57bd-4a15-83dd-21044345fd74" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_ae5f34e8-0986-44f1-8ea9-b6df3c9faa71" xlink:to="loc_us-gaap_SubsequentEventMember_7fc64937-57bd-4a15-83dd-21044345fd74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_54954b79-df7c-463d-9ddd-c92f7f9def6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_b32668e6-e94e-4bb5-b2ad-592b65bc11f2" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_54954b79-df7c-463d-9ddd-c92f7f9def6a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_54954b79-df7c-463d-9ddd-c92f7f9def6a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_54954b79-df7c-463d-9ddd-c92f7f9def6a" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_54954b79-df7c-463d-9ddd-c92f7f9def6a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_f1a24171-ebdf-4068-9345-7158466c62e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_54954b79-df7c-463d-9ddd-c92f7f9def6a" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_f1a24171-ebdf-4068-9345-7158466c62e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NewYorkStatePublicServiceCommissionMember_8364527c-6f17-4a57-8c55-8224e21ad1ab" xlink:href="nrg-20231231.xsd#nrg_NewYorkStatePublicServiceCommissionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_f1a24171-ebdf-4068-9345-7158466c62e7" xlink:to="loc_nrg_NewYorkStatePublicServiceCommissionMember_8364527c-6f17-4a57-8c55-8224e21ad1ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7881fcec-8757-46f5-9294-3e8753606975" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_b32668e6-e94e-4bb5-b2ad-592b65bc11f2" xlink:to="loc_srt_RangeAxis_7881fcec-8757-46f5-9294-3e8753606975" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7881fcec-8757-46f5-9294-3e8753606975_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7881fcec-8757-46f5-9294-3e8753606975" xlink:to="loc_srt_RangeMember_7881fcec-8757-46f5-9294-3e8753606975_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d286992c-7e45-4ef6-8f18-a79071a513db" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7881fcec-8757-46f5-9294-3e8753606975" xlink:to="loc_srt_RangeMember_d286992c-7e45-4ef6-8f18-a79071a513db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f803bfbb-4214-4b02-a451-5e5aa7ad5e92" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d286992c-7e45-4ef6-8f18-a79071a513db" xlink:to="loc_srt_MinimumMember_f803bfbb-4214-4b02-a451-5e5aa7ad5e92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_dd0ee0dc-38ba-448b-8aba-0deedf670284" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d286992c-7e45-4ef6-8f18-a79071a513db" xlink:to="loc_srt_MaximumMember_dd0ee0dc-38ba-448b-8aba-0deedf670284" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_09bac408-d55f-4dcd-9ff9-9aa5af7785d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_65b17b85-2400-4ee4-9857-5a443c6a5177" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_09bac408-d55f-4dcd-9ff9-9aa5af7785d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfCompanysRetailSuppliersNotified_fa3070fc-a24f-489e-b189-12385768407f" xlink:href="nrg-20231231.xsd#nrg_NumberOfCompanysRetailSuppliersNotified"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_65b17b85-2400-4ee4-9857-5a443c6a5177" xlink:to="loc_nrg_NumberOfCompanysRetailSuppliersNotified_fa3070fc-a24f-489e-b189-12385768407f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_NumberOfCompliantProductsAuthorizedByRegulatoryAgency_622f8ed1-863e-4ae3-8d60-922af68e1b22" xlink:href="nrg-20231231.xsd#nrg_NumberOfCompliantProductsAuthorizedByRegulatoryAgency"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_65b17b85-2400-4ee4-9857-5a443c6a5177" xlink:to="loc_nrg_NumberOfCompliantProductsAuthorizedByRegulatoryAgency_622f8ed1-863e-4ae3-8d60-922af68e1b22" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/GuaranteesScheduleofMaximumPotentialExposureDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#GuaranteesScheduleofMaximumPotentialExposureDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/GuaranteesScheduleofMaximumPotentialExposureDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsLineItems_d4ee9c8a-10e6-418e-bc5d-7dd67cb00e81" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_416438b8-c404-4b8c-99cd-5adfcf2d0122" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGuaranteeObligationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_d4ee9c8a-10e6-418e-bc5d-7dd67cb00e81" xlink:to="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_416438b8-c404-4b8c-99cd-5adfcf2d0122" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_30c0c5bf-a3df-411f-b1ee-b4609bdbc91a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_416438b8-c404-4b8c-99cd-5adfcf2d0122" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_30c0c5bf-a3df-411f-b1ee-b4609bdbc91a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_30c0c5bf-a3df-411f-b1ee-b4609bdbc91a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_30c0c5bf-a3df-411f-b1ee-b4609bdbc91a" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_30c0c5bf-a3df-411f-b1ee-b4609bdbc91a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_16666288-daf7-42be-bd09-b7b5525f91b2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_30c0c5bf-a3df-411f-b1ee-b4609bdbc91a" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_16666288-daf7-42be-bd09-b7b5525f91b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LettersOfCreditAndSuretyBondsMember_041cff5b-6b94-427f-9bfd-834283099814" xlink:href="nrg-20231231.xsd#nrg_LettersOfCreditAndSuretyBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_16666288-daf7-42be-bd09-b7b5525f91b2" xlink:to="loc_nrg_LettersOfCreditAndSuretyBondsMember_041cff5b-6b94-427f-9bfd-834283099814" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetSalesGuaranteeObligationsMember_5374e9eb-314b-4d7d-be6a-38861293163b" xlink:href="nrg-20231231.xsd#nrg_AssetSalesGuaranteeObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_16666288-daf7-42be-bd09-b7b5525f91b2" xlink:to="loc_nrg_AssetSalesGuaranteeObligationsMember_5374e9eb-314b-4d7d-be6a-38861293163b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeTypeOtherMember_c9492c4c-6047-48cb-a507-84feff275d45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeTypeOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_16666288-daf7-42be-bd09-b7b5525f91b2" xlink:to="loc_us-gaap_GuaranteeTypeOtherMember_c9492c4c-6047-48cb-a507-84feff275d45" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GuaranteeMaturityLessThanOneYear_8c299814-1c7e-4270-aedc-6e545108fd60" xlink:href="nrg-20231231.xsd#nrg_GuaranteeMaturityLessThanOneYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_d4ee9c8a-10e6-418e-bc5d-7dd67cb00e81" xlink:to="loc_nrg_GuaranteeMaturityLessThanOneYear_8c299814-1c7e-4270-aedc-6e545108fd60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GuaranteeMaturityBetweenOneToThreeYears_60ccc2ca-121b-4e34-9437-43e60bfceb10" xlink:href="nrg-20231231.xsd#nrg_GuaranteeMaturityBetweenOneToThreeYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_d4ee9c8a-10e6-418e-bc5d-7dd67cb00e81" xlink:to="loc_nrg_GuaranteeMaturityBetweenOneToThreeYears_60ccc2ca-121b-4e34-9437-43e60bfceb10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GuaranteeMaturityBetweenThreeToFiveYears_feeeda24-3285-4009-8b2a-c990f4be6f2a" xlink:href="nrg-20231231.xsd#nrg_GuaranteeMaturityBetweenThreeToFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_d4ee9c8a-10e6-418e-bc5d-7dd67cb00e81" xlink:to="loc_nrg_GuaranteeMaturityBetweenThreeToFiveYears_feeeda24-3285-4009-8b2a-c990f4be6f2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GuaranteeMaturityGreaterThanFiveYears_3cc70cef-6684-4a98-a9f3-aab236ef3d01" xlink:href="nrg-20231231.xsd#nrg_GuaranteeMaturityGreaterThanFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_d4ee9c8a-10e6-418e-bc5d-7dd67cb00e81" xlink:to="loc_nrg_GuaranteeMaturityGreaterThanFiveYears_3cc70cef-6684-4a98-a9f3-aab236ef3d01" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GuaranteeObligationsEstimatedExposure_88c1f26e-fa0b-4186-b8f3-1929873a57a2" xlink:href="nrg-20231231.xsd#nrg_GuaranteeObligationsEstimatedExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_d4ee9c8a-10e6-418e-bc5d-7dd67cb00e81" xlink:to="loc_nrg_GuaranteeObligationsEstimatedExposure_88c1f26e-fa0b-4186-b8f3-1929873a57a2" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/GuaranteesNarrativeDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#GuaranteesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/GuaranteesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsLineItems_98ff6087-46d8-47bf-8d9e-3ae103996da0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_e080c70d-3ff7-443a-a494-685fd5ac69cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGuaranteeObligationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_98ff6087-46d8-47bf-8d9e-3ae103996da0" xlink:to="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_e080c70d-3ff7-443a-a494-685fd5ac69cf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_5b6bf07d-8d34-40b1-9dfd-05d292c1ad4b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_e080c70d-3ff7-443a-a494-685fd5ac69cf" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_5b6bf07d-8d34-40b1-9dfd-05d292c1ad4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_5b6bf07d-8d34-40b1-9dfd-05d292c1ad4b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_5b6bf07d-8d34-40b1-9dfd-05d292c1ad4b" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_5b6bf07d-8d34-40b1-9dfd-05d292c1ad4b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_925e8385-03d9-4963-b198-ff5e00547257" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_5b6bf07d-8d34-40b1-9dfd-05d292c1ad4b" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_925e8385-03d9-4963-b198-ff5e00547257" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_LettersOfCreditAndSuretyBondsMember_e8eb66c8-3fb4-4951-8466-08c17a7f35e3" xlink:href="nrg-20231231.xsd#nrg_LettersOfCreditAndSuretyBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_925e8385-03d9-4963-b198-ff5e00547257" xlink:to="loc_nrg_LettersOfCreditAndSuretyBondsMember_e8eb66c8-3fb4-4951-8466-08c17a7f35e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_AssetSalesGuaranteeObligationsMember_a4b8195a-d5ef-4bdf-9eee-a3083b4a000a" xlink:href="nrg-20231231.xsd#nrg_AssetSalesGuaranteeObligationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_925e8385-03d9-4963-b198-ff5e00547257" xlink:to="loc_nrg_AssetSalesGuaranteeObligationsMember_a4b8195a-d5ef-4bdf-9eee-a3083b4a000a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GuaranteeObligationsEstimatedExposure_223f6f80-9932-4393-bbb9-6297f8be2905" xlink:href="nrg-20231231.xsd#nrg_GuaranteeObligationsEstimatedExposure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_98ff6087-46d8-47bf-8d9e-3ae103996da0" xlink:to="loc_nrg_GuaranteeObligationsEstimatedExposure_223f6f80-9932-4393-bbb9-6297f8be2905" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_GuaranteeObligationsLettersofCreditandSuretyBondsMaximumExpirationPeriod_e2dbe964-f8f5-4cde-8c18-56c619d13cff" xlink:href="nrg-20231231.xsd#nrg_GuaranteeObligationsLettersofCreditandSuretyBondsMaximumExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_98ff6087-46d8-47bf-8d9e-3ae103996da0" xlink:to="loc_nrg_GuaranteeObligationsLettersofCreditandSuretyBondsMaximumExpirationPeriod_e2dbe964-f8f5-4cde-8c18-56c619d13cff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_42ccbb11-0c09-4fd9-bfd7-c28fe10dcf0d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_98ff6087-46d8-47bf-8d9e-3ae103996da0" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_42ccbb11-0c09-4fd9-bfd7-c28fe10dcf0d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/JointlyOwnedPlantDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#JointlyOwnedPlantDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/JointlyOwnedPlantDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantInterestsLineItems_b1791a62-914f-4ca8-84c0-48b8d51a498b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantInterestsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantInterestsTable_3b5d5b3c-2188-48fd-99e7-34ecf72bf129" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantInterestsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantInterestsLineItems_b1791a62-914f-4ca8-84c0-48b8d51a498b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantInterestsTable_3b5d5b3c-2188-48fd-99e7-34ecf72bf129" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantAxis_6766455c-b42c-471d-bd18-40cddcffba9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantInterestsTable_3b5d5b3c-2188-48fd-99e7-34ecf72bf129" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantAxis_6766455c-b42c-471d-bd18-40cddcffba9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_6766455c-b42c-471d-bd18-40cddcffba9b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_6766455c-b42c-471d-bd18-40cddcffba9b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_6766455c-b42c-471d-bd18-40cddcffba9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantDomain_70f0ae9c-3ed4-479d-a048-10bf77b23be7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantAxis_6766455c-b42c-471d-bd18-40cddcffba9b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantDomain_70f0ae9c-3ed4-479d-a048-10bf77b23be7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_CedarBayouUnit4Member_11eeafaa-f814-4165-b851-863c984ca3ed" xlink:href="nrg-20231231.xsd#nrg_CedarBayouUnit4Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantDomain_70f0ae9c-3ed4-479d-a048-10bf77b23be7" xlink:to="loc_nrg_CedarBayouUnit4Member_11eeafaa-f814-4165-b851-863c984ca3ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare_f0d68b7f-15bc-4319-a5ec-97380ed26fbd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantInterestsLineItems_b1791a62-914f-4ca8-84c0-48b8d51a498b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare_f0d68b7f-15bc-4319-a5ec-97380ed26fbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService_1e4b599f-2a3d-41c4-a296-9e152728522b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantInterestsLineItems_b1791a62-914f-4ca8-84c0-48b8d51a498b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService_1e4b599f-2a3d-41c4-a296-9e152728522b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation_fac58757-9697-4840-91b7-f16c6a17c4d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantInterestsLineItems_b1791a62-914f-4ca8-84c0-48b8d51a498b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation_fac58757-9697-4840-91b7-f16c6a17c4d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress_5b618401-1f27-4a34-b52d-4760b570d9ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_JointlyOwnedUtilityPlantInterestsLineItems_b1791a62-914f-4ca8-84c0-48b8d51a498b" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress_5b618401-1f27-4a34-b52d-4760b570d9ff" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.nrgenergy.com/role/SCHEDULEIIVALUATIONANDQUALIFYINGACCOUNTSDetails" xlink:type="simple" xlink:href="nrg-20231231.xsd#SCHEDULEIIVALUATIONANDQUALIFYINGACCOUNTSDetails"/>
  <link:definitionLink xlink:role="http://www.nrgenergy.com/role/SCHEDULEIIVALUATIONANDQUALIFYINGACCOUNTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63054733-530b-4e11-84d3-0684a248ce49" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_bb68417b-ac7e-4575-9af1-7b34e2195431" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63054733-530b-4e11-84d3-0684a248ce49" xlink:to="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_bb68417b-ac7e-4575-9af1-7b34e2195431" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_590368d6-6c8f-4799-860f-7f2f6c37185f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_bb68417b-ac7e-4575-9af1-7b34e2195431" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_590368d6-6c8f-4799-860f-7f2f6c37185f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_590368d6-6c8f-4799-860f-7f2f6c37185f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_590368d6-6c8f-4799-860f-7f2f6c37185f" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_590368d6-6c8f-4799-860f-7f2f6c37185f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_c184bac1-edab-49fc-a5d6-6cd7e8ab73bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_590368d6-6c8f-4799-860f-7f2f6c37185f" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_c184bac1-edab-49fc-a5d6-6cd7e8ab73bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForCreditLossMember_9dd0b8f3-92d8-43c5-83d9-107941de81d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForCreditLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_c184bac1-edab-49fc-a5d6-6cd7e8ab73bd" xlink:to="loc_us-gaap_AllowanceForCreditLossMember_9dd0b8f3-92d8-43c5-83d9-107941de81d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_11298c48-e260-4f09-b68b-c4430156c620" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_c184bac1-edab-49fc-a5d6-6cd7e8ab73bd" xlink:to="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_11298c48-e260-4f09-b68b-c4430156c620" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_530ca714-2b54-4f1c-a3aa-11d497c93ee7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63054733-530b-4e11-84d3-0684a248ce49" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_530ca714-2b54-4f1c-a3aa-11d497c93ee7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_798d70d0-b863-42ed-a558-370c6a83a6ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_530ca714-2b54-4f1c-a3aa-11d497c93ee7" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_798d70d0-b863-42ed-a558-370c6a83a6ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_b1f89118-73d2-4e3d-8b17-98c04e833880" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_530ca714-2b54-4f1c-a3aa-11d497c93ee7" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_b1f89118-73d2-4e3d-8b17-98c04e833880" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts_a6c4cd87-37f6-4bde-9749-6f3e7ee707e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_530ca714-2b54-4f1c-a3aa-11d497c93ee7" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts_a6c4cd87-37f6-4bde-9749-6f3e7ee707e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_6e799073-b526-4786-8228-4b2a9561dc67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesDeductions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_530ca714-2b54-4f1c-a3aa-11d497c93ee7" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_6e799073-b526-4786-8228-4b2a9561dc67" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_5789c114-a99e-4754-af11-655bfbbae80f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-roles-2023.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate202006Member" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingStandardsUpdate202006Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember" xlink:to="loc_us-gaap_AccountingStandardsUpdate202006Member" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_DeferredStockUnitsMember_c29b19d6-f3b2-4c46-9db0-20195a3d8624" xlink:href="nrg-20231231.xsd#nrg_DeferredStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_nrg_DeferredStockUnitsMember_c29b19d6-f3b2-4c46-9db0-20195a3d8624" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RelativePerformanceStockUnitsMember_40a25093-b3e0-4748-8160-1956a023c8a6" xlink:href="nrg-20231231.xsd#nrg_RelativePerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_nrg_RelativePerformanceStockUnitsMember_40a25093-b3e0-4748-8160-1956a023c8a6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RolloverRestrictedStockUnitsRSUMember_b60251f8-6d13-46cd-a5a1-bed15fa53d95" xlink:href="nrg-20231231.xsd#nrg_RolloverRestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_nrg_RolloverRestrictedStockUnitsRSUMember_b60251f8-6d13-46cd-a5a1-bed15fa53d95" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RestrictedStockUnitsPostAcquisitionMember_3d743663-3b21-4de0-9233-0bf8296da298" xlink:href="nrg-20231231.xsd#nrg_RestrictedStockUnitsPostAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_nrg_RestrictedStockUnitsPostAcquisitionMember_3d743663-3b21-4de0-9233-0bf8296da298" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_PerformanceSharesMember" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_PhantomRestrictedStockUnitsPRSUsMember_f40549d6-cab3-4fbb-88bc-88715f59b803" xlink:href="nrg-20231231.xsd#nrg_PhantomRestrictedStockUnitsPRSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_nrg_PhantomRestrictedStockUnitsPRSUsMember_f40549d6-cab3-4fbb-88bc-88715f59b803" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_ElizabethKillingerMember_c8b23d42-071d-4724-a7b7-00dca59a20ab" xlink:href="nrg-20231231.xsd#nrg_ElizabethKillingerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_nrg_ElizabethKillingerMember_c8b23d42-071d-4724-a7b7-00dca59a20ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_nrg_RaseshPatelMember_dcaf99a0-6103-44d2-ac12-0b1bdf48d0c3" xlink:href="nrg-20231231.xsd#nrg_RaseshPatelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_nrg_RaseshPatelMember_dcaf99a0-6103-44d2-ac12-0b1bdf48d0c3" xlink:type="arc" order="3"/>
  </link:definitionLink>
</link:linkbase>
