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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:9fdc8bec-fa65-48d2-8843-267367d448cd,g:0297437f-d758-490f-a47b-63a9905ba1e4-->
<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.talenenergy.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="simple" xlink:href="tln-20260331.xsd#CondensedConsolidatedStatementsOfOperationsUnaudited"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_b54e5bcd-2a62-4d1a-b673-f0191ff907da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_StatementTable_b54e5bcd-2a62-4d1a-b673-f0191ff907da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_08398ac0-7019-4804-ad69-1b90dc881980" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_b54e5bcd-2a62-4d1a-b673-f0191ff907da" xlink:to="loc_srt_ProductOrServiceAxis_08398ac0-7019-4804-ad69-1b90dc881980" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_08398ac0-7019-4804-ad69-1b90dc881980_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_08398ac0-7019-4804-ad69-1b90dc881980" xlink:to="loc_srt_ProductsAndServicesDomain_08398ac0-7019-4804-ad69-1b90dc881980_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_c13ed3c9-b435-4040-bf98-735af3a15cdd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_08398ac0-7019-4804-ad69-1b90dc881980" xlink:to="loc_srt_ProductsAndServicesDomain_c13ed3c9-b435-4040-bf98-735af3a15cdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnergyAndOtherMember_9428ee47-b342-4a56-ae4d-4178f322995c" xlink:href="tln-20260331.xsd#tln_EnergyAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c13ed3c9-b435-4040-bf98-735af3a15cdd" xlink:to="loc_tln_EnergyAndOtherMember_9428ee47-b342-4a56-ae4d-4178f322995c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingRevenueCapacityMember_3cd68908-07fb-4223-af22-a8e26d5e0f4c" xlink:href="tln-20260331.xsd#tln_OperatingRevenueCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c13ed3c9-b435-4040-bf98-735af3a15cdd" xlink:to="loc_tln_OperatingRevenueCapacityMember_3cd68908-07fb-4223-af22-a8e26d5e0f4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CommodityContractsUnrealizedGainLossMember_2d6a0964-fa24-40cb-ab31-76f3d14f96f8" xlink:href="tln-20260331.xsd#tln_CommodityContractsUnrealizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c13ed3c9-b435-4040-bf98-735af3a15cdd" xlink:to="loc_tln_CommodityContractsUnrealizedGainLossMember_2d6a0964-fa24-40cb-ab31-76f3d14f96f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_1731e72a-3ab1-402e-b0dc-2b857828fb84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_Revenues_1731e72a-3ab1-402e-b0dc-2b857828fb84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingExpenseFuelUsedAndPurchasedPower_1e97d621-ecee-4f34-9512-8b3d8c77964a" xlink:href="tln-20260331.xsd#tln_OperatingExpenseFuelUsedAndPurchasedPower"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_tln_OperatingExpenseFuelUsedAndPurchasedPower_1e97d621-ecee-4f34-9512-8b3d8c77964a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfNuclearFuelLease_bcb1ce36-6eb4-43f9-b90d-e7412608a6c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfNuclearFuelLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_AmortizationOfNuclearFuelLease_bcb1ce36-6eb4-43f9-b90d-e7412608a6c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_UnrealizedGainLossOnCommodityContractsEnergyExpenses_69c1ab71-357e-4e9e-809c-62ea84eab164" xlink:href="tln-20260331.xsd#tln_UnrealizedGainLossOnCommodityContractsEnergyExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_tln_UnrealizedGainLossOnCommodityContractsEnergyExpenses_69c1ab71-357e-4e9e-809c-62ea84eab164" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnergyExpenses_acdf07d4-f937-488e-b4ac-a66be0c84360" xlink:href="tln-20260331.xsd#tln_EnergyExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_tln_EnergyExpenses_acdf07d4-f937-488e-b4ac-a66be0c84360" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_8d00b19e-62d2-431b-a957-afe0cd65385b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_OperatingExpensesAbstract_8d00b19e-62d2-431b-a957-afe0cd65385b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperationMaintenanceAndDevelopmentExpense_318fe84d-4258-4e36-ae01-461c8a8e971f" xlink:href="tln-20260331.xsd#tln_OperationMaintenanceAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8d00b19e-62d2-431b-a957-afe0cd65385b" xlink:to="loc_tln_OperationMaintenanceAndDevelopmentExpense_318fe84d-4258-4e36-ae01-461c8a8e971f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_e9c3fdea-24f5-470c-8929-efec26d0fd20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8d00b19e-62d2-431b-a957-afe0cd65385b" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_e9c3fdea-24f5-470c-8929-efec26d0fd20" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_dfea285d-5f7a-40a7-ae0c-24e32be90e38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8d00b19e-62d2-431b-a957-afe0cd65385b" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_dfea285d-5f7a-40a7-ae0c-24e32be90e38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_4048f558-8f42-4d93-a3b5-803936dead44" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_8d00b19e-62d2-431b-a957-afe0cd65385b" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_4048f558-8f42-4d93-a3b5-803936dead44" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_2b0e516c-e5ed-4c2f-8d95-78e097a381f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_OperatingIncomeLoss_2b0e516c-e5ed-4c2f-8d95-78e097a381f7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_e5ee1fe8-91ed-4a02-a205-9102a0059c2d" xlink:href="tln-20260331.xsd#tln_GainLossOnNuclearDecommissioningTrustFundsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_e5ee1fe8-91ed-4a02-a205-9102a0059c2d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDebtExpense_ae92a803-938e-4184-a525-eca19c0cfcee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestAndDebtExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_InterestAndDebtExpense_ae92a803-938e-4184-a525-eca19c0cfcee" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_e0804729-8786-4500-aaaf-79b5034140e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_e0804729-8786-4500-aaaf-79b5034140e7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_58b59d49-a967-4e79-9b42-af01ab0dc8c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_58b59d49-a967-4e79-9b42-af01ab0dc8c3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_a32e403d-0340-4292-a099-6cc3e5299d36" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_a32e403d-0340-4292-a099-6cc3e5299d36" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_163b9bf4-23c4-4a0f-bbef-53d32d090404" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_ProfitLoss_163b9bf4-23c4-4a0f-bbef-53d32d090404" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_b70c1174-11ec-4b49-b371-5e52ed8b6ff9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_25a06232-c52a-45df-b39b-5bc9999e78ab" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_b70c1174-11ec-4b49-b371-5e52ed8b6ff9" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_515d1332-b5b3-42d5-ba9e-23eb35df6e66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_b70c1174-11ec-4b49-b371-5e52ed8b6ff9" xlink:to="loc_us-gaap_EarningsPerShareBasic_515d1332-b5b3-42d5-ba9e-23eb35df6e66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_a6ddfec5-3813-4cbc-9fdc-09cf8fcd5013" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_b70c1174-11ec-4b49-b371-5e52ed8b6ff9" xlink:to="loc_us-gaap_EarningsPerShareDiluted_a6ddfec5-3813-4cbc-9fdc-09cf8fcd5013" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_29ec9978-a0d8-449e-a2ee-6282ecd09763" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_b70c1174-11ec-4b49-b371-5e52ed8b6ff9" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_29ec9978-a0d8-449e-a2ee-6282ecd09763" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_0c5ba216-e97a-4920-843c-46a487b5ccea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_b70c1174-11ec-4b49-b371-5e52ed8b6ff9" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_0c5ba216-e97a-4920-843c-46a487b5ccea" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CondensedConsolidatedStatementsOfEquityUnaudited" xlink:type="simple" xlink:href="tln-20260331.xsd#CondensedConsolidatedStatementsOfEquityUnaudited"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CondensedConsolidatedStatementsOfEquityUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_d307b83a-8a28-49fe-8e15-f646b9a30b27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_7fd99eec-d44f-4cdb-9ea1-862dbce5f369" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_d307b83a-8a28-49fe-8e15-f646b9a30b27" xlink:to="loc_us-gaap_StatementTable_7fd99eec-d44f-4cdb-9ea1-862dbce5f369" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f16400f6-1b71-492e-9031-3efcf18c4e1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7fd99eec-d44f-4cdb-9ea1-862dbce5f369" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f16400f6-1b71-492e-9031-3efcf18c4e1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f16400f6-1b71-492e-9031-3efcf18c4e1b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f16400f6-1b71-492e-9031-3efcf18c4e1b" xlink:to="loc_us-gaap_EquityComponentDomain_f16400f6-1b71-492e-9031-3efcf18c4e1b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_690eeb38-40ec-4d37-bee6-7028d223ff7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f16400f6-1b71-492e-9031-3efcf18c4e1b" xlink:to="loc_us-gaap_EquityComponentDomain_690eeb38-40ec-4d37-bee6-7028d223ff7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_0832a369-a8b8-4f65-9ed3-71e0372117ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_690eeb38-40ec-4d37-bee6-7028d223ff7e" xlink:to="loc_us-gaap_CommonStockMember_0832a369-a8b8-4f65-9ed3-71e0372117ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_3ab87858-8520-47b0-8cb0-16a248ad582d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_690eeb38-40ec-4d37-bee6-7028d223ff7e" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_3ab87858-8520-47b0-8cb0-16a248ad582d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_29b40f13-ae24-41fa-8823-6a6880c2dd4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_690eeb38-40ec-4d37-bee6-7028d223ff7e" xlink:to="loc_us-gaap_RetainedEarningsMember_29b40f13-ae24-41fa-8823-6a6880c2dd4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_d76fdb32-6639-4b41-a9b9-837cc8a93a87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_690eeb38-40ec-4d37-bee6-7028d223ff7e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_d76fdb32-6639-4b41-a9b9-837cc8a93a87" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_2200132d-f9e9-455e-988a-dd2fe6836fd2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_690eeb38-40ec-4d37-bee6-7028d223ff7e" xlink:to="loc_us-gaap_TreasuryStockCommonMember_2200132d-f9e9-455e-988a-dd2fe6836fd2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d307b83a-8a28-49fe-8e15-f646b9a30b27" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_5c40a8c1-d134-459e-8f68-dece5fabddea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_5c40a8c1-d134-459e-8f68-dece5fabddea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7b2a2437-eadd-42cb-abb4-1b353f0fc2e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_7b2a2437-eadd-42cb-abb4-1b353f0fc2e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_1b6876f3-146a-4da2-8028-550669d5202c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_ProfitLoss_1b6876f3-146a-4da2-8028-550669d5202c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_fa35e41d-5fff-46d8-8449-008f7e18e919" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_fa35e41d-5fff-46d8-8449-008f7e18e919" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_961d2c88-2f31-4a59-a73c-7dfee829e1b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_961d2c88-2f31-4a59-a73c-7dfee829e1b0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_7a06b6b9-2ea2-4dbf-9eec-1ab67914e087" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_7a06b6b9-2ea2-4dbf-9eec-1ab67914e087" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_019d2433-31f0-7b88-bfa2-3f66491ae38e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockRetiredCostMethodAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_TreasuryStockRetiredCostMethodAmount_019d2433-31f0-7b88-bfa2-3f66491ae38e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansAndShareBasedPaymentArrangement_019dba7c-f841-7265-8b6f-36d4aeb289b0" xlink:href="tln-20260331.xsd#tln_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansAndShareBasedPaymentArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_tln_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansAndShareBasedPaymentArrangement_019dba7c-f841-7265-8b6f-36d4aeb289b0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019c9585-ef60-7df4-85b8-6476afb4e41a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091bcaaf-61cf-4a87-b409-f4171fd692e6" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019c9585-ef60-7df4-85b8-6476afb4e41a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_92f37320-2545-4147-97aa-4ecbc8d58b22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_b6be2948-d69b-4055-9bd3-2191039fb046" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/BusinessBasisofPresentationandSummaryofSignificantAccountingPoliciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94840f1f-ff09-4c2c-a769-d95b6590e05b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_95a11b14-7ef8-47bb-9075-14f2f132ca9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94840f1f-ff09-4c2c-a769-d95b6590e05b" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_95a11b14-7ef8-47bb-9075-14f2f132ca9c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c4ee4c0f-e4bb-4db8-bdac-7ebbb4739459" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_95a11b14-7ef8-47bb-9075-14f2f132ca9c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c4ee4c0f-e4bb-4db8-bdac-7ebbb4739459" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c4ee4c0f-e4bb-4db8-bdac-7ebbb4739459_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c4ee4c0f-e4bb-4db8-bdac-7ebbb4739459" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_c4ee4c0f-e4bb-4db8-bdac-7ebbb4739459_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_f5acf22f-38ba-4925-bdb1-5db1268e59b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_c4ee4c0f-e4bb-4db8-bdac-7ebbb4739459" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_f5acf22f-38ba-4925-bdb1-5db1268e59b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelMember_c08a58d6-ad8e-40be-894a-d21fcdbc9b09" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_f5acf22f-38ba-4925-bdb1-5db1268e59b0" xlink:to="loc_us-gaap_NuclearFuelMember_c08a58d6-ad8e-40be-894a-d21fcdbc9b09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PowerGenerationCapacity_6182551a-5999-424f-a84e-36a43b97db37" xlink:href="tln-20260331.xsd#tln_PowerGenerationCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_94840f1f-ff09-4c2c-a769-d95b6590e05b" xlink:to="loc_tln_PowerGenerationCapacity_6182551a-5999-424f-a84e-36a43b97db37" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofNetNotionalVolumesofOpenCommodityDerivativesandInterestRateDerivativesDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofNetNotionalVolumesofOpenCommodityDerivativesandInterestRateDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesScheduleofNetNotionalVolumesofOpenCommodityDerivativesandInterestRateDerivativesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_23dc3d3a-55fd-46f6-a630-41233f236530" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_03042b90-cc74-4b93-ae3a-c80e777bb3c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_23dc3d3a-55fd-46f6-a630-41233f236530" xlink:to="loc_us-gaap_DerivativeTable_03042b90-cc74-4b93-ae3a-c80e777bb3c2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_30772741-9315-42b2-b066-f9d143c59154" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_03042b90-cc74-4b93-ae3a-c80e777bb3c2" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_30772741-9315-42b2-b066-f9d143c59154" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_30772741-9315-42b2-b066-f9d143c59154_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_30772741-9315-42b2-b066-f9d143c59154" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_30772741-9315-42b2-b066-f9d143c59154_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_d04ff61c-cf28-46de-8b76-c1acd53aa134" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_30772741-9315-42b2-b066-f9d143c59154" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_d04ff61c-cf28-46de-8b76-c1acd53aa134" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_a86cda06-0d49-4122-a1e6-c82ac8264a42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_d04ff61c-cf28-46de-8b76-c1acd53aa134" xlink:to="loc_us-gaap_CommodityContractMember_a86cda06-0d49-4122-a1e6-c82ac8264a42" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_97ed3f97-a0c2-4e60-9dae-f835a05984e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_d04ff61c-cf28-46de-8b76-c1acd53aa134" xlink:to="loc_us-gaap_InterestRateContractMember_97ed3f97-a0c2-4e60-9dae-f835a05984e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_9afe1a5b-2296-4b7b-9c61-7af0673fb4c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_03042b90-cc74-4b93-ae3a-c80e777bb3c2" xlink:to="loc_us-gaap_PositionAxis_9afe1a5b-2296-4b7b-9c61-7af0673fb4c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_9afe1a5b-2296-4b7b-9c61-7af0673fb4c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_9afe1a5b-2296-4b7b-9c61-7af0673fb4c6" xlink:to="loc_us-gaap_PositionDomain_9afe1a5b-2296-4b7b-9c61-7af0673fb4c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_2542a88e-ea7c-4bf8-a63a-86a367fec3e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_9afe1a5b-2296-4b7b-9c61-7af0673fb4c6" xlink:to="loc_us-gaap_PositionDomain_2542a88e-ea7c-4bf8-a63a-86a367fec3e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_7055ec35-f47b-4be5-bc48-a573ea136a39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_2542a88e-ea7c-4bf8-a63a-86a367fec3e2" xlink:to="loc_us-gaap_ShortMember_7055ec35-f47b-4be5-bc48-a573ea136a39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_2220a7fc-deca-43b2-b5f1-65c3cd9e0b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_2542a88e-ea7c-4bf8-a63a-86a367fec3e2" xlink:to="loc_us-gaap_LongMember_2220a7fc-deca-43b2-b5f1-65c3cd9e0b4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_99501e40-8c05-4b24-9463-1a014031fdfc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_23dc3d3a-55fd-46f6-a630-41233f236530" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_99501e40-8c05-4b24-9463-1a014031fdfc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_f25068e8-67a2-428d-b42f-6ef02dabb02f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountMass"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_23dc3d3a-55fd-46f6-a630-41233f236530" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_f25068e8-67a2-428d-b42f-6ef02dabb02f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_c13a1617-3036-4dbd-b133-4768b20bb34e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_23dc3d3a-55fd-46f6-a630-41233f236530" xlink:to="loc_us-gaap_DerivativeNotionalAmount_c13a1617-3036-4dbd-b133-4768b20bb34e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesNarrativeDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_9519210e-5860-4a37-a251-c60add073723" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_4f489024-36ad-40eb-8d0d-8cdd2e9dea42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_9519210e-5860-4a37-a251-c60add073723" xlink:to="loc_us-gaap_DerivativeTable_4f489024-36ad-40eb-8d0d-8cdd2e9dea42" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f02570bf-ef92-40aa-95c1-acd3ffc19728" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4f489024-36ad-40eb-8d0d-8cdd2e9dea42" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f02570bf-ef92-40aa-95c1-acd3ffc19728" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f02570bf-ef92-40aa-95c1-acd3ffc19728_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f02570bf-ef92-40aa-95c1-acd3ffc19728" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f02570bf-ef92-40aa-95c1-acd3ffc19728_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_5d2b721e-889e-41e1-87c2-c94ebff0dc84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f02570bf-ef92-40aa-95c1-acd3ffc19728" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_5d2b721e-889e-41e1-87c2-c94ebff0dc84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TotalNetCreditExposureMember_bc79f3a7-dfc6-49c3-9ef0-b792e18216e8" xlink:href="tln-20260331.xsd#tln_TotalNetCreditExposureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_5d2b721e-889e-41e1-87c2-c94ebff0dc84" xlink:to="loc_tln_TotalNetCreditExposureMember_bc79f3a7-dfc6-49c3-9ef0-b792e18216e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_4ffe8e68-6e18-4284-ae76-247b507542b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4f489024-36ad-40eb-8d0d-8cdd2e9dea42" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_4ffe8e68-6e18-4284-ae76-247b507542b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_4ffe8e68-6e18-4284-ae76-247b507542b1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_4ffe8e68-6e18-4284-ae76-247b507542b1" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_4ffe8e68-6e18-4284-ae76-247b507542b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_6c86d2db-92cc-46d6-a469-640e43657892" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_4ffe8e68-6e18-4284-ae76-247b507542b1" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_6c86d2db-92cc-46d6-a469-640e43657892" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditConcentrationRiskMember_6170152d-c9c5-40d7-80ab-96c7caad5568" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_6c86d2db-92cc-46d6-a469-640e43657892" xlink:to="loc_us-gaap_CreditConcentrationRiskMember_6170152d-c9c5-40d7-80ab-96c7caad5568" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_c9746b22-1ca5-41cc-adb4-a557d1da6810" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4f489024-36ad-40eb-8d0d-8cdd2e9dea42" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_c9746b22-1ca5-41cc-adb4-a557d1da6810" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_c9746b22-1ca5-41cc-adb4-a557d1da6810_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_c9746b22-1ca5-41cc-adb4-a557d1da6810" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_c9746b22-1ca5-41cc-adb4-a557d1da6810_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_6753b39e-ee9e-408c-9223-35eba4a04424" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis_c9746b22-1ca5-41cc-adb4-a557d1da6810" xlink:to="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_6753b39e-ee9e-408c-9223-35eba4a04424" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TenLargestSingleNetCreditExposuresMember_b125ab00-59db-4648-a420-f45f1b8886d7" xlink:href="tln-20260331.xsd#tln_TenLargestSingleNetCreditExposuresMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueConcentrationOfRiskDisclosureItemsDomain_6753b39e-ee9e-408c-9223-35eba4a04424" xlink:to="loc_tln_TenLargestSingleNetCreditExposuresMember_b125ab00-59db-4648-a420-f45f1b8886d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditDerivativeMaximumExposureUndiscounted_f874f3b1-b0dc-4bc6-8a3b-cd15720c3288" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditDerivativeMaximumExposureUndiscounted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_9519210e-5860-4a37-a251-c60add073723" xlink:to="loc_us-gaap_CreditDerivativeMaximumExposureUndiscounted_f874f3b1-b0dc-4bc6-8a3b-cd15720c3288" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CreditDerivativeMaximumExposureUndiscountedNet_4062827d-7215-4897-bf42-adf664b6d73f" xlink:href="tln-20260331.xsd#tln_CreditDerivativeMaximumExposureUndiscountedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_9519210e-5860-4a37-a251-c60add073723" xlink:to="loc_tln_CreditDerivativeMaximumExposureUndiscountedNet_4062827d-7215-4897-bf42-adf664b6d73f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_2a5a73b8-e89b-4610-9fe3-45574b06ba6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_9519210e-5860-4a37-a251-c60add073723" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_2a5a73b8-e89b-4610-9fe3-45574b06ba6e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesBalanceSheetsPresentationDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesBalanceSheetsPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesBalanceSheetsPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_c1e66122-be17-4c99-8ce5-9511e4f4139e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_9f94968e-989d-44e2-bd7a-2845c99e356a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_c1e66122-be17-4c99-8ce5-9511e4f4139e" xlink:to="loc_us-gaap_DerivativeTable_9f94968e-989d-44e2-bd7a-2845c99e356a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_af1f6f72-1494-46ff-b28d-778422a581b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9f94968e-989d-44e2-bd7a-2845c99e356a" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_af1f6f72-1494-46ff-b28d-778422a581b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_af1f6f72-1494-46ff-b28d-778422a581b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_af1f6f72-1494-46ff-b28d-778422a581b8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_af1f6f72-1494-46ff-b28d-778422a581b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_410c6155-a829-4757-a58d-f328d3e2f68e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_af1f6f72-1494-46ff-b28d-778422a581b8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_410c6155-a829-4757-a58d-f328d3e2f68e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_3293c079-40f9-4b4c-9887-b79013ce0bc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_410c6155-a829-4757-a58d-f328d3e2f68e" xlink:to="loc_us-gaap_CommodityContractMember_3293c079-40f9-4b4c-9887-b79013ce0bc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_bde98807-6eaf-4fcb-8dce-c3139f2ebae4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_410c6155-a829-4757-a58d-f328d3e2f68e" xlink:to="loc_us-gaap_InterestRateContractMember_bde98807-6eaf-4fcb-8dce-c3139f2ebae4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_a2dbe01a-4784-4611-beb1-4c5c2030e42d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_c1e66122-be17-4c99-8ce5-9511e4f4139e" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_a2dbe01a-4784-4611-beb1-4c5c2030e42d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_f93bfe43-7fa4-4b8c-a2df-a38c1a7896bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_c1e66122-be17-4c99-8ce5-9511e4f4139e" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_f93bfe43-7fa4-4b8c-a2df-a38c1a7896bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsNoncurrent_d2fc7912-26e2-4cf0-9b84-d42406198957" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_c1e66122-be17-4c99-8ce5-9511e4f4139e" xlink:to="loc_us-gaap_DerivativeAssetsNoncurrent_d2fc7912-26e2-4cf0-9b84-d42406198957" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_5c5c957f-f156-428a-aaa1-721c061550d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_c1e66122-be17-4c99-8ce5-9511e4f4139e" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_5c5c957f-f156-428a-aaa1-721c061550d4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesStatementsofOperationsPresentationDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#RiskManagementDerivativeInstrumentsandHedgingActivitiesStatementsofOperationsPresentationDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RiskManagementDerivativeInstrumentsandHedgingActivitiesStatementsofOperationsPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_1f8a6b8c-1711-452a-8a60-ce0d6b7f4709" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_70a02eca-fdc9-4012-9f96-05a2ed6a6784" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_1f8a6b8c-1711-452a-8a60-ce0d6b7f4709" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_70a02eca-fdc9-4012-9f96-05a2ed6a6784" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_ff4facd2-0b1c-481e-b316-cd3adede0a18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_70a02eca-fdc9-4012-9f96-05a2ed6a6784" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_ff4facd2-0b1c-481e-b316-cd3adede0a18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_ff4facd2-0b1c-481e-b316-cd3adede0a18_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_ff4facd2-0b1c-481e-b316-cd3adede0a18" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_ff4facd2-0b1c-481e-b316-cd3adede0a18_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_7cf74bfb-02fb-45bf-ac09-2cfa228d7992" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_ff4facd2-0b1c-481e-b316-cd3adede0a18" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_7cf74bfb-02fb-45bf-ac09-2cfa228d7992" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnergyRevenuesMember_b4d7fc6d-9550-4c31-9a38-a27b40772c6b" xlink:href="tln-20260331.xsd#tln_EnergyRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_7cf74bfb-02fb-45bf-ac09-2cfa228d7992" xlink:to="loc_tln_EnergyRevenuesMember_b4d7fc6d-9550-4c31-9a38-a27b40772c6b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_FuelAndEnergyPurchasesMember_d388727a-050e-4253-b3ba-abe645604598" xlink:href="tln-20260331.xsd#tln_FuelAndEnergyPurchasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_7cf74bfb-02fb-45bf-ac09-2cfa228d7992" xlink:to="loc_tln_FuelAndEnergyPurchasesMember_d388727a-050e-4253-b3ba-abe645604598" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingRevenuesMember_320f645f-547a-438c-b13b-ca327b826ba6" xlink:href="tln-20260331.xsd#tln_OperatingRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_7cf74bfb-02fb-45bf-ac09-2cfa228d7992" xlink:to="loc_tln_OperatingRevenuesMember_320f645f-547a-438c-b13b-ca327b826ba6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnergyExpensesMember_7a5a48b9-08ff-4474-a102-3cd3dd79a39f" xlink:href="tln-20260331.xsd#tln_EnergyExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_7cf74bfb-02fb-45bf-ac09-2cfa228d7992" xlink:to="loc_tln_EnergyExpensesMember_7a5a48b9-08ff-4474-a102-3cd3dd79a39f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_c987d29b-6bb5-4a3a-a5f3-22e1c7af64a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_70a02eca-fdc9-4012-9f96-05a2ed6a6784" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_c987d29b-6bb5-4a3a-a5f3-22e1c7af64a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c987d29b-6bb5-4a3a-a5f3-22e1c7af64a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c987d29b-6bb5-4a3a-a5f3-22e1c7af64a3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c987d29b-6bb5-4a3a-a5f3-22e1c7af64a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_035c29bd-25b2-4a78-a44a-27e3773dae62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c987d29b-6bb5-4a3a-a5f3-22e1c7af64a3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_035c29bd-25b2-4a78-a44a-27e3773dae62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_a0ca9a0d-54bf-49be-9c26-59af13155c54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_035c29bd-25b2-4a78-a44a-27e3773dae62" xlink:to="loc_us-gaap_InterestRateContractMember_a0ca9a0d-54bf-49be-9c26-59af13155c54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfCommodityContracts_60ed8648-6200-426d-8696-46af78343a23" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_1f8a6b8c-1711-452a-8a60-ce0d6b7f4709" xlink:to="loc_us-gaap_GainLossOnSaleOfCommodityContracts_60ed8648-6200-426d-8696-46af78343a23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_18b624e9-63a8-48e2-b47a-21ed28768065" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrealizedGainLossOnCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_1f8a6b8c-1711-452a-8a60-ce0d6b7f4709" xlink:to="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_18b624e9-63a8-48e2-b47a-21ed28768065" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_99549c17-61b9-4951-905d-ba25155b9b80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_1f8a6b8c-1711-452a-8a60-ce0d6b7f4709" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_99549c17-61b9-4951-905d-ba25155b9b80" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RevenueScheduleofComponentsofOperatingRevenuesDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#RevenueScheduleofComponentsofOperatingRevenuesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RevenueScheduleofComponentsofOperatingRevenuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_9aa7c31e-45c1-42d2-84f6-580e9f0960d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_f1c895fd-696a-48b8-851a-9e37e1e51d45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9aa7c31e-45c1-42d2-84f6-580e9f0960d2" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_f1c895fd-696a-48b8-851a-9e37e1e51d45" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_ad531a1e-7e2d-4cc0-b5d1-4c9ee3be21f3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_f1c895fd-696a-48b8-851a-9e37e1e51d45" xlink:to="loc_srt_ProductOrServiceAxis_ad531a1e-7e2d-4cc0-b5d1-4c9ee3be21f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_ad531a1e-7e2d-4cc0-b5d1-4c9ee3be21f3_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_ad531a1e-7e2d-4cc0-b5d1-4c9ee3be21f3" xlink:to="loc_srt_ProductsAndServicesDomain_ad531a1e-7e2d-4cc0-b5d1-4c9ee3be21f3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_ce1818af-0789-44b2-9aaa-d5108beb7bfb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_ad531a1e-7e2d-4cc0-b5d1-4c9ee3be21f3" xlink:to="loc_srt_ProductsAndServicesDomain_ce1818af-0789-44b2-9aaa-d5108beb7bfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ElectricitySalesAndAncillaryServicesMember_dd664fdd-198f-4329-a984-8565496ba0fd" xlink:href="tln-20260331.xsd#tln_ElectricitySalesAndAncillaryServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_ce1818af-0789-44b2-9aaa-d5108beb7bfb" xlink:to="loc_tln_ElectricitySalesAndAncillaryServicesMember_dd664fdd-198f-4329-a984-8565496ba0fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingRevenueCapacityMember_f370448e-4107-45c1-a839-bbdbf5255380" xlink:href="tln-20260331.xsd#tln_OperatingRevenueCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_ce1818af-0789-44b2-9aaa-d5108beb7bfb" xlink:to="loc_tln_OperatingRevenueCapacityMember_f370448e-4107-45c1-a839-bbdbf5255380" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PhysicalElectricitySalesBilateralContractsOtherMember_a0b29f04-4bb5-4bfe-8099-04a7876e59ba" xlink:href="tln-20260331.xsd#tln_PhysicalElectricitySalesBilateralContractsOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_ce1818af-0789-44b2-9aaa-d5108beb7bfb" xlink:to="loc_tln_PhysicalElectricitySalesBilateralContractsOtherMember_a0b29f04-4bb5-4bfe-8099-04a7876e59ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_83f9e4a2-6c7b-4726-8a28-6644311680a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9aa7c31e-45c1-42d2-84f6-580e9f0960d2" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_83f9e4a2-6c7b-4726-8a28-6644311680a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_687466fd-a9ea-4c00-bed3-4caeddf2d927" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9aa7c31e-45c1-42d2-84f6-580e9f0960d2" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_687466fd-a9ea-4c00-bed3-4caeddf2d927" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncome_edb0800e-33b4-44b2-933a-e6fc75f03324" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9aa7c31e-45c1-42d2-84f6-580e9f0960d2" xlink:to="loc_us-gaap_OtherIncome_edb0800e-33b4-44b2-933a-e6fc75f03324" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_064feeac-d298-4f65-9a8b-c7314ea7281e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9aa7c31e-45c1-42d2-84f6-580e9f0960d2" xlink:to="loc_us-gaap_Revenues_064feeac-d298-4f65-9a8b-c7314ea7281e" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#RevenueScheduleofFuturePerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_158218b0-32be-42b0-a5a3-3415a4844bd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_158218b0-32be-42b0-a5a3-3415a4844bd6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_26d796d5-4f86-4ae1-ae44-0dae8afa212a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_158218b0-32be-42b0-a5a3-3415a4844bd6" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_26d796d5-4f86-4ae1-ae44-0dae8afa212a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_158218b0-32be-42b0-a5a3-3415a4844bd6" xlink:to="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_85d6b20b-32f1-4957-aa39-7f0147156a4a_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:to="loc_srt_ProductsAndServicesDomain_85d6b20b-32f1-4957-aa39-7f0147156a4a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_ece59486-d4d7-455e-9e7b-a310cfb2b03c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:to="loc_srt_ProductsAndServicesDomain_ece59486-d4d7-455e-9e7b-a310cfb2b03c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingRevenueCapacityMember_019df34a-0e82-7710-b869-e4bdc6e3e501" xlink:href="tln-20260331.xsd#tln_OperatingRevenueCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_ece59486-d4d7-455e-9e7b-a310cfb2b03c" xlink:to="loc_tln_OperatingRevenueCapacityMember_019df34a-0e82-7710-b869-e4bdc6e3e501" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_e26edd8b-37ed-4c2b-a1f0-c442cc9bf9cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_e26edd8b-37ed-4c2b-a1f0-c442cc9bf9cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_158ae15e-4467-4031-9765-5c95c58346fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_158ae15e-4467-4031-9765-5c95c58346fb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails_1" xlink:type="simple" xlink:href="tln-20260331.xsd#RevenueScheduleofFuturePerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/RevenueScheduleofFuturePerformanceObligationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_158218b0-32be-42b0-a5a3-3415a4844bd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_158218b0-32be-42b0-a5a3-3415a4844bd6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_158218b0-32be-42b0-a5a3-3415a4844bd6" xlink:to="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_85d6b20b-32f1-4957-aa39-7f0147156a4a_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:to="loc_srt_ProductsAndServicesDomain_85d6b20b-32f1-4957-aa39-7f0147156a4a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_ece59486-d4d7-455e-9e7b-a310cfb2b03c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_85d6b20b-32f1-4957-aa39-7f0147156a4a" xlink:to="loc_srt_ProductsAndServicesDomain_ece59486-d4d7-455e-9e7b-a310cfb2b03c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperatingRevenueCapacityMember_019df34a-0e82-7710-b869-e4bdc6e3e501" xlink:href="tln-20260331.xsd#tln_OperatingRevenueCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_ece59486-d4d7-455e-9e7b-a310cfb2b03c" xlink:to="loc_tln_OperatingRevenueCapacityMember_019df34a-0e82-7710-b869-e4bdc6e3e501" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_e26edd8b-37ed-4c2b-a1f0-c442cc9bf9cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_e26edd8b-37ed-4c2b-a1f0-c442cc9bf9cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_158ae15e-4467-4031-9765-5c95c58346fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_6216fdd2-aed8-4c1b-a04c-64aad2fe2f9c" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_158ae15e-4467-4031-9765-5c95c58346fb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofUnrealizedGainLossonNuclearDecommissioningTrustFundsDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#NuclearDecommissioningTrustFundsScheduleofUnrealizedGainLossonNuclearDecommissioningTrustFundsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofUnrealizedGainLossonNuclearDecommissioningTrustFundsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_38380fa7-3831-471f-b9da-3aa93896c68a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_38380fa7-3831-471f-b9da-3aa93896c68a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_fa28f439-6e5d-4e0a-80b0-2bc1531ef9b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_38380fa7-3831-471f-b9da-3aa93896c68a" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_fa28f439-6e5d-4e0a-80b0-2bc1531ef9b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_fa28f439-6e5d-4e0a-80b0-2bc1531ef9b5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_fa28f439-6e5d-4e0a-80b0-2bc1531ef9b5" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_fa28f439-6e5d-4e0a-80b0-2bc1531ef9b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_7ec4add6-d91f-4e3c-afe2-5bb22786eed7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_fa28f439-6e5d-4e0a-80b0-2bc1531ef9b5" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_7ec4add6-d91f-4e3c-afe2-5bb22786eed7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsMember_59b67d15-4d46-49ab-b595-11fd52504c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_7ec4add6-d91f-4e3c-afe2-5bb22786eed7" xlink:to="loc_us-gaap_CashEquivalentsMember_59b67d15-4d46-49ab-b595-11fd52504c7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_bda5af67-8d0e-46fa-952a-570d6c47f7c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_bda5af67-8d0e-46fa-952a-570d6c47f7c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_21f6a435-a1fc-4071-8daf-f7d4d018a4f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_21f6a435-a1fc-4071-8daf-f7d4d018a4f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCost_1c9c3205-ee3d-4d51-b22a-e93206df1ea5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNiCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_EquitySecuritiesFvNiCost_1c9c3205-ee3d-4d51-b22a-e93206df1ea5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax_0ca8e540-affe-4191-8f08-a4c6f3f2ddde" xlink:href="tln-20260331.xsd#tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedGainBeforeTax_0ca8e540-affe-4191-8f08-a4c6f3f2ddde" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax_596e2001-defb-4673-a8a1-6777d095f5fc" xlink:href="tln-20260331.xsd#tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_tln_EquitySecuritiesFVNIAccumulatedGrossUnrealizedLossBeforeTax_596e2001-defb-4673-a8a1-6777d095f5fc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_bbb39b7c-e9f8-464e-acd5-ce3d9341d038" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_bbb39b7c-e9f8-464e-acd5-ce3d9341d038" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_06cd4d7e-5f5e-46c3-bc1e-1bfe92f88f50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_06cd4d7e-5f5e-46c3-bc1e-1bfe92f88f50" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_618d731f-e59c-417f-95fa-37f9263e036d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_618d731f-e59c-417f-95fa-37f9263e036d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_3cc962b4-2fcb-4d13-8bbb-e070067e55bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_3cc962b4-2fcb-4d13-8bbb-e070067e55bb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_24c53894-6d48-48d5-9789-bc561c503051" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_24c53894-6d48-48d5-9789-bc561c503051" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReceivablesPayablesNetAmortizedCost_917eee12-b3af-4bd1-8ce2-5d5b7e78bac7" xlink:href="tln-20260331.xsd#tln_ReceivablesPayablesNetAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_tln_ReceivablesPayablesNetAmortizedCost_917eee12-b3af-4bd1-8ce2-5d5b7e78bac7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReceivablesPayablesNetFairValue_59c16505-e6ab-4412-9af9-7f8947aff18c" xlink:href="tln-20260331.xsd#tln_ReceivablesPayablesNetFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_tln_ReceivablesPayablesNetFairValue_59c16505-e6ab-4412-9af9-7f8947aff18c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DecommissioningFundInvestmentsAmortizedCost_7dd40f66-6bea-49f1-82ae-d570b80fb5ec" xlink:href="tln-20260331.xsd#tln_DecommissioningFundInvestmentsAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_tln_DecommissioningFundInvestmentsAmortizedCost_7dd40f66-6bea-49f1-82ae-d570b80fb5ec" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedGainBeforeTax_6f311df5-8524-461f-bb0f-3c93666fbe44" xlink:href="tln-20260331.xsd#tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedGainBeforeTax_6f311df5-8524-461f-bb0f-3c93666fbe44" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedLossBeforeTax_9f20e068-bc6d-4813-ad5a-6c5819ab5c9b" xlink:href="tln-20260331.xsd#tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_tln_DecommissioningFundInvestmentsAccumulatedGrossUnrealizedLossBeforeTax_9f20e068-bc6d-4813-ad5a-6c5819ab5c9b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_93b43ffa-39e0-4048-8b92-9626b7cc10ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_73834c12-721c-466d-8a54-dcdd8765387b" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_93b43ffa-39e0-4048-8b92-9626b7cc10ba" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofAvailableforSaleDebtSecuritiesWithUnrealizedLossesDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#NuclearDecommissioningTrustFundsScheduleofAvailableforSaleDebtSecuritiesWithUnrealizedLossesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/NuclearDecommissioningTrustFundsScheduleofAvailableforSaleDebtSecuritiesWithUnrealizedLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a96f9276-a6a0-4265-b55c-99e7abfe4aec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_44d1af50-1e52-4860-8322-6199231c6943" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a96f9276-a6a0-4265-b55c-99e7abfe4aec" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_44d1af50-1e52-4860-8322-6199231c6943" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_7594b342-5ba2-4d89-95bc-3b74e1040e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_44d1af50-1e52-4860-8322-6199231c6943" xlink:to="loc_us-gaap_FinancialInstrumentAxis_7594b342-5ba2-4d89-95bc-3b74e1040e8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7594b342-5ba2-4d89-95bc-3b74e1040e8d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7594b342-5ba2-4d89-95bc-3b74e1040e8d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7594b342-5ba2-4d89-95bc-3b74e1040e8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ccca5363-6dc2-44d7-949c-487fe893c592" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7594b342-5ba2-4d89-95bc-3b74e1040e8d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ccca5363-6dc2-44d7-949c-487fe893c592" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_80bc8e16-fea6-499e-850f-0b51267ffdee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ccca5363-6dc2-44d7-949c-487fe893c592" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_80bc8e16-fea6-499e-850f-0b51267ffdee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_b02fbdbd-3ad7-403f-8e85-fe23b4d385e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ccca5363-6dc2-44d7-949c-487fe893c592" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_b02fbdbd-3ad7-403f-8e85-fe23b4d385e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentDebtSecuritiesMember_64f259c5-a40a-4b92-a941-0d96c4f4a8ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ccca5363-6dc2-44d7-949c-487fe893c592" xlink:to="loc_us-gaap_USGovernmentDebtSecuritiesMember_64f259c5-a40a-4b92-a941-0d96c4f4a8ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_2cbc13bf-b31b-454c-902e-26a1fa359481" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a96f9276-a6a0-4265-b55c-99e7abfe4aec" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_2cbc13bf-b31b-454c-902e-26a1fa359481" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_f8e693e2-72c6-4bf3-9bdc-61a0e0789fcb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a96f9276-a6a0-4265-b55c-99e7abfe4aec" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_f8e693e2-72c6-4bf3-9bdc-61a0e0789fcb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_9a0a4b87-e751-4c8f-b4ba-d1c3317e7292" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a96f9276-a6a0-4265-b55c-99e7abfe4aec" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_9a0a4b87-e751-4c8f-b4ba-d1c3317e7292" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_784372f5-059c-415a-b1b5-3c27894ece06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_6f23c0ae-fb1f-4edc-ac41-b7b54ee79018" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_784372f5-059c-415a-b1b5-3c27894ece06" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_6f23c0ae-fb1f-4edc-ac41-b7b54ee79018" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_f75c931a-468d-46b0-8b00-aad8553d2b09" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_6f23c0ae-fb1f-4edc-ac41-b7b54ee79018" xlink:to="loc_srt_RangeAxis_f75c931a-468d-46b0-8b00-aad8553d2b09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f75c931a-468d-46b0-8b00-aad8553d2b09_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_f75c931a-468d-46b0-8b00-aad8553d2b09" xlink:to="loc_srt_RangeMember_f75c931a-468d-46b0-8b00-aad8553d2b09_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_80c55307-3591-4bf2-a53e-1887ac69fef3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_f75c931a-468d-46b0-8b00-aad8553d2b09" xlink:to="loc_srt_RangeMember_80c55307-3591-4bf2-a53e-1887ac69fef3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_228379fe-c5f5-422b-a15c-5acf1c76fa6f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_80c55307-3591-4bf2-a53e-1887ac69fef3" xlink:to="loc_srt_MinimumMember_228379fe-c5f5-422b-a15c-5acf1c76fa6f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_7847acd6-9a49-4a46-9ddb-d15e52b237e7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_80c55307-3591-4bf2-a53e-1887ac69fef3" xlink:to="loc_srt_MaximumMember_7847acd6-9a49-4a46-9ddb-d15e52b237e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_06893247-8d38-4767-945d-ab8dcef3e800" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_6f23c0ae-fb1f-4edc-ac41-b7b54ee79018" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_06893247-8d38-4767-945d-ab8dcef3e800" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_06893247-8d38-4767-945d-ab8dcef3e800_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_06893247-8d38-4767-945d-ab8dcef3e800" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_06893247-8d38-4767-945d-ab8dcef3e800_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_53e383dc-038c-40fe-8d32-b5c1de2dd033" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_06893247-8d38-4767-945d-ab8dcef3e800" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_53e383dc-038c-40fe-8d32-b5c1de2dd033" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ElectricityGenerationMember_324ae2b5-1650-41ad-aad9-d7e8bcdc3a02" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ElectricityGenerationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_53e383dc-038c-40fe-8d32-b5c1de2dd033" xlink:to="loc_us-gaap_ElectricityGenerationMember_324ae2b5-1650-41ad-aad9-d7e8bcdc3a02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelMember_7215fa50-8184-4092-9bd1-dab1b563d0cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_53e383dc-038c-40fe-8d32-b5c1de2dd033" xlink:to="loc_us-gaap_NuclearFuelMember_7215fa50-8184-4092-9bd1-dab1b563d0cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_6d4c212a-1b44-4f1d-8ec7-57f0413205cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentOtherTypesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_53e383dc-038c-40fe-8d32-b5c1de2dd033" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentOtherTypesMember_6d4c212a-1b44-4f1d-8ec7-57f0413205cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_34f5099f-f908-4010-90d5-14de916c3db8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_53e383dc-038c-40fe-8d32-b5c1de2dd033" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_34f5099f-f908-4010-90d5-14de916c3db8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_595b8088-eb9b-4209-a4c1-7a1f6bdf0a50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_53e383dc-038c-40fe-8d32-b5c1de2dd033" xlink:to="loc_us-gaap_ConstructionInProgressMember_595b8088-eb9b-4209-a4c1-7a1f6bdf0a50" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_d05270d6-17bb-4808-80ec-919faa894f5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_784372f5-059c-415a-b1b5-3c27894ece06" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_d05270d6-17bb-4808-80ec-919faa894f5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ef971170-fb2b-4941-a195-47ce57376cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_d05270d6-17bb-4808-80ec-919faa894f5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_ef971170-fb2b-4941-a195-47ce57376cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_98cfa7ae-f4b0-4be3-8d36-189568889dbd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_d05270d6-17bb-4808-80ec-919faa894f5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_98cfa7ae-f4b0-4be3-8d36-189568889dbd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_d609ef71-11a2-4f67-ad05-a22f1dfcd6d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_d05270d6-17bb-4808-80ec-919faa894f5c" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_d609ef71-11a2-4f67-ad05-a22f1dfcd6d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_ed83892b-4e54-42ab-af43-ef415a1a1a93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_d05270d6-17bb-4808-80ec-919faa894f5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_ed83892b-4e54-42ab-af43-ef415a1a1a93" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AssetRetirementObligationsandAccruedEnvironmentalCostsScheduleofDisaggregationofAssetRetirementObligationsDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#AssetRetirementObligationsandAccruedEnvironmentalCostsScheduleofDisaggregationofAssetRetirementObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AssetRetirementObligationsandAccruedEnvironmentalCostsScheduleofDisaggregationofAssetRetirementObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_tln_AssetRetirementObligationLineItems_70b4c230-3446-4caa-b8ff-35294bf200f7" xlink:href="tln-20260331.xsd#tln_AssetRetirementObligationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AssetRetirementObligationTable_bfa743a3-f6f5-49b7-89af-849557f3b720" xlink:href="tln-20260331.xsd#tln_AssetRetirementObligationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_tln_AssetRetirementObligationLineItems_70b4c230-3446-4caa-b8ff-35294bf200f7" xlink:to="loc_tln_AssetRetirementObligationTable_bfa743a3-f6f5-49b7-89af-849557f3b720" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_7c9190bc-cb40-4b50-88d9-708f7d26b4b0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_tln_AssetRetirementObligationTable_bfa743a3-f6f5-49b7-89af-849557f3b720" xlink:to="loc_srt_EnergyAxis_7c9190bc-cb40-4b50-88d9-708f7d26b4b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_7c9190bc-cb40-4b50-88d9-708f7d26b4b0_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_7c9190bc-cb40-4b50-88d9-708f7d26b4b0" xlink:to="loc_srt_EnergyDomain_7c9190bc-cb40-4b50-88d9-708f7d26b4b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_53151ace-7e7a-4e47-816f-54c3f8e7e8a9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_7c9190bc-cb40-4b50-88d9-708f7d26b4b0" xlink:to="loc_srt_EnergyDomain_53151ace-7e7a-4e47-816f-54c3f8e7e8a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NuclearFuelMember_7a220b70-b9ee-4d37-a84b-0df424084143" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_53151ace-7e7a-4e47-816f-54c3f8e7e8a9" xlink:to="loc_us-gaap_NuclearFuelMember_7a220b70-b9ee-4d37-a84b-0df424084143" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NonNuclearFuelMember_f452afa1-6070-40d9-b71c-c694cf0d8ad9" xlink:href="tln-20260331.xsd#tln_NonNuclearFuelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_53151ace-7e7a-4e47-816f-54c3f8e7e8a9" xlink:to="loc_tln_NonNuclearFuelMember_f452afa1-6070-40d9-b71c-c694cf0d8ad9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligation_3bdddb14-f93c-4834-aa3a-3a409d068632" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetRetirementObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_AssetRetirementObligationLineItems_70b4c230-3446-4caa-b8ff-35294bf200f7" xlink:to="loc_us-gaap_AssetRetirementObligation_3bdddb14-f93c-4834-aa3a-3a409d068632" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CommitmentsandContingenciesRegulatoryMattersDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#CommitmentsandContingenciesRegulatoryMattersDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CommitmentsandContingenciesRegulatoryMattersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_f62debc4-ca1c-4a85-bd95-8acd06ec8414" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_us-gaap_OtherCommitmentsTable_f62debc4-ca1c-4a85-bd95-8acd06ec8414" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_975ef58e-4250-4516-a300-584b1257c236" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_f62debc4-ca1c-4a85-bd95-8acd06ec8414" xlink:to="loc_srt_RangeAxis_975ef58e-4250-4516-a300-584b1257c236" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_975ef58e-4250-4516-a300-584b1257c236_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_975ef58e-4250-4516-a300-584b1257c236" xlink:to="loc_srt_RangeMember_975ef58e-4250-4516-a300-584b1257c236_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_088a4671-5f3c-4b07-bd02-16b43edace2b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_975ef58e-4250-4516-a300-584b1257c236" xlink:to="loc_srt_RangeMember_088a4671-5f3c-4b07-bd02-16b43edace2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_11ab30c2-e851-4e10-805c-bc534dd0612f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_088a4671-5f3c-4b07-bd02-16b43edace2b" xlink:to="loc_srt_MinimumMember_11ab30c2-e851-4e10-805c-bc534dd0612f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_9c5d76b7-d459-44a0-a2ce-3343af2bb01c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_088a4671-5f3c-4b07-bd02-16b43edace2b" xlink:to="loc_srt_MaximumMember_9c5d76b7-d459-44a0-a2ce-3343af2bb01c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019dc094-fdf6-7c02-b8ea-16d2083deb5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_f62debc4-ca1c-4a85-bd95-8acd06ec8414" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019dc094-fdf6-7c02-b8ea-16d2083deb5c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019dc094-fdf6-7c02-b8ea-16d2083deb5c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019dc094-fdf6-7c02-b8ea-16d2083deb5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019dc094-fdf6-7c02-b8ea-16d2083deb5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019dc094-fdf6-7e56-8cd7-bdbfa35da956" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019dc094-fdf6-7c02-b8ea-16d2083deb5c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019dc094-fdf6-7e56-8cd7-bdbfa35da956" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_BrandonShoresMember_019dc094-fdf6-7290-95a4-0f0d6e88f6c6" xlink:href="tln-20260331.xsd#tln_BrandonShoresMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019dc094-fdf6-7e56-8cd7-bdbfa35da956" xlink:to="loc_tln_BrandonShoresMember_019dc094-fdf6-7290-95a4-0f0d6e88f6c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_WagnerMember_019dc094-fdf6-735d-a299-a61f8c26bd28" xlink:href="tln-20260331.xsd#tln_WagnerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019dc094-fdf6-7e56-8cd7-bdbfa35da956" xlink:to="loc_tln_WagnerMember_019dc094-fdf6-735d-a299-a61f8c26bd28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_RequestedDelayDuration_7add576e-5130-4550-bd1b-7943516e24ae" xlink:href="tln-20260331.xsd#tln_RequestedDelayDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_RequestedDelayDuration_7add576e-5130-4550-bd1b-7943516e24ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfFERCFilings_a50ba8ca-40d3-485b-aef7-fd19dde5c50a" xlink:href="tln-20260331.xsd#tln_NumberOfFERCFilings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_NumberOfFERCFilings_a50ba8ca-40d3-485b-aef7-fd19dde5c50a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfDeliveryYears_36507445-ca61-4543-abc3-0672683e5346" xlink:href="tln-20260331.xsd#tln_NumberOfDeliveryYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_NumberOfDeliveryYears_36507445-ca61-4543-abc3-0672683e5346" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CollarOnCapacityPrice_6de3fd77-5a45-493c-a2ad-ce6f6cf227b0" xlink:href="tln-20260331.xsd#tln_CollarOnCapacityPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_CollarOnCapacityPrice_6de3fd77-5a45-493c-a2ad-ce6f6cf227b0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_FixedCostAnnualPayments_019dc094-fdf6-7a9a-b8b4-3f76df9029bd" xlink:href="tln-20260331.xsd#tln_FixedCostAnnualPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_FixedCostAnnualPayments_019dc094-fdf6-7a9a-b8b4-3f76df9029bd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_FixedCostPricePerMWPerDay_019dc094-fdf6-7d9a-95c0-94219786fde6" xlink:href="tln-20260331.xsd#tln_FixedCostPricePerMWPerDay"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_FixedCostPricePerMWPerDay_019dc094-fdf6-7d9a-95c0-94219786fde6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PerformanceHoldBackPerYear_019dc094-fdf6-78e9-894c-290456b4f1a8" xlink:href="tln-20260331.xsd#tln_PerformanceHoldBackPerYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_PerformanceHoldBackPerYear_019dc094-fdf6-78e9-894c-290456b4f1a8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfStatesInPJM_019c967a-e723-7e62-964a-a5c76ecfaeef" xlink:href="tln-20260331.xsd#tln_NumberOfStatesInPJM"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_NumberOfStatesInPJM_019c967a-e723-7e62-964a-a5c76ecfaeef" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReliabilityBackstopAuctionBaseloadCapacityContractTerm_019c967e-f9dc-7b3e-8cc6-f96f0286c2f6" xlink:href="tln-20260331.xsd#tln_ReliabilityBackstopAuctionBaseloadCapacityContractTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_ReliabilityBackstopAuctionBaseloadCapacityContractTerm_019c967e-f9dc-7b3e-8cc6-f96f0286c2f6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfBaseResidualAuctions_019c967f-6c45-76f0-bf86-f411d046f042" xlink:href="tln-20260331.xsd#tln_NumberOfBaseResidualAuctions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_0a8b7ce3-5709-4163-b8ed-72a80f7f36c5" xlink:to="loc_tln_NumberOfBaseResidualAuctions_019c967f-6c45-76f0-bf86-f411d046f042" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CommitmentsandContingenciesEnvironmentalMattersDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#CommitmentsandContingenciesEnvironmentalMattersDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CommitmentsandContingenciesEnvironmentalMattersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_2d93a997-6b61-4830-90f2-304c0cb82b57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_bfd0dba5-fe2b-4ca2-ba98-18a787ea4f3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_2d93a997-6b61-4830-90f2-304c0cb82b57" xlink:to="loc_us-gaap_OtherCommitmentsTable_bfd0dba5-fe2b-4ca2-ba98-18a787ea4f3c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_f070031b-2a8b-4094-8eef-629a268db56e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_bfd0dba5-fe2b-4ca2-ba98-18a787ea4f3c" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_f070031b-2a8b-4094-8eef-629a268db56e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_f070031b-2a8b-4094-8eef-629a268db56e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_f070031b-2a8b-4094-8eef-629a268db56e" xlink:to="loc_us-gaap_LossContingencyNatureDomain_f070031b-2a8b-4094-8eef-629a268db56e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_96fd570c-a451-4de6-83ac-61d33e94a9d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_f070031b-2a8b-4094-8eef-629a268db56e" xlink:to="loc_us-gaap_LossContingencyNatureDomain_96fd570c-a451-4de6-83ac-61d33e94a9d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPAMATSRuleMember_019dd384-0b4f-7d5f-8a99-f0004d099cab" xlink:href="tln-20260331.xsd#tln_EnvironmentalMattersEPAMATSRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_96fd570c-a451-4de6-83ac-61d33e94a9d7" xlink:to="loc_tln_EnvironmentalMattersEPAMATSRuleMember_019dd384-0b4f-7d5f-8a99-f0004d099cab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPAGHGRuleMember_6b3dc511-5189-494c-b92c-2c768aef09d1" xlink:href="tln-20260331.xsd#tln_EnvironmentalMattersEPAGHGRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_96fd570c-a451-4de6-83ac-61d33e94a9d7" xlink:to="loc_tln_EnvironmentalMattersEPAGHGRuleMember_6b3dc511-5189-494c-b92c-2c768aef09d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPAELGRuleMember_30672f0d-92d5-43c8-af6f-616248dda208" xlink:href="tln-20260331.xsd#tln_EnvironmentalMattersEPAELGRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_96fd570c-a451-4de6-83ac-61d33e94a9d7" xlink:to="loc_tln_EnvironmentalMattersEPAELGRuleMember_30672f0d-92d5-43c8-af6f-616248dda208" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EnvironmentalMattersEPACCRRuleMember_ce2cd6ac-a43e-4d06-9444-7928435c61c2" xlink:href="tln-20260331.xsd#tln_EnvironmentalMattersEPACCRRuleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_96fd570c-a451-4de6-83ac-61d33e94a9d7" xlink:to="loc_tln_EnvironmentalMattersEPACCRRuleMember_ce2cd6ac-a43e-4d06-9444-7928435c61c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LossContingencyNumberOfStates_78d8db35-f55e-451c-b9b3-e7d91d59102d" xlink:href="tln-20260331.xsd#tln_LossContingencyNumberOfStates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_2d93a997-6b61-4830-90f2-304c0cb82b57" xlink:to="loc_tln_LossContingencyNumberOfStates_78d8db35-f55e-451c-b9b3-e7d91d59102d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_NumberOfStatesRepresentedByCoalitions_86052c7d-b26c-40e3-8b42-a7e0b92e9934" xlink:href="tln-20260331.xsd#tln_NumberOfStatesRepresentedByCoalitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_2d93a997-6b61-4830-90f2-304c0cb82b57" xlink:to="loc_tln_NumberOfStatesRepresentedByCoalitions_86052c7d-b26c-40e3-8b42-a7e0b92e9934" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LossContingencyNumberOfIndustryGroups_61db90fe-f45f-454b-a5c6-ca9aa8b8aff3" xlink:href="tln-20260331.xsd#tln_LossContingencyNumberOfIndustryGroups"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_2d93a997-6b61-4830-90f2-304c0cb82b57" xlink:to="loc_tln_LossContingencyNumberOfIndustryGroups_61db90fe-f45f-454b-a5c6-ca9aa8b8aff3" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/CommitmentsandContingenciesGuaranteesandOtherAssurancesDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#CommitmentsandContingenciesGuaranteesandOtherAssurancesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/CommitmentsandContingenciesGuaranteesandOtherAssurancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_19e6852e-31c3-4a87-81b2-5d94185fe590" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_16a9fa1b-bfaf-4604-be32-598276dfccc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_19e6852e-31c3-4a87-81b2-5d94185fe590" xlink:to="loc_us-gaap_OtherCommitmentsTable_16a9fa1b-bfaf-4604-be32-598276dfccc2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_e470027a-9662-4017-97df-a1dd1c108a49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_16a9fa1b-bfaf-4604-be32-598276dfccc2" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_e470027a-9662-4017-97df-a1dd1c108a49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_e470027a-9662-4017-97df-a1dd1c108a49_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_e470027a-9662-4017-97df-a1dd1c108a49" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_e470027a-9662-4017-97df-a1dd1c108a49_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_ebd7e106-6324-48c6-a3ff-3125297fb7a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_e470027a-9662-4017-97df-a1dd1c108a49" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_ebd7e106-6324-48c6-a3ff-3125297fb7a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SuretyBondMember_1ea9ea4e-4027-4335-9dc3-a03fdf20868b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SuretyBondMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_ebd7e106-6324-48c6-a3ff-3125297fb7a1" xlink:to="loc_us-gaap_SuretyBondMember_1ea9ea4e-4027-4335-9dc3-a03fdf20868b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_9ab345e4-76b9-4b94-865d-c1819b7f32d6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_16a9fa1b-bfaf-4604-be32-598276dfccc2" xlink:to="loc_srt_ConsolidatedEntitiesAxis_9ab345e4-76b9-4b94-865d-c1819b7f32d6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_9ab345e4-76b9-4b94-865d-c1819b7f32d6_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_9ab345e4-76b9-4b94-865d-c1819b7f32d6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_9ab345e4-76b9-4b94-865d-c1819b7f32d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_f7de3f6c-43f2-4190-89ba-f16c00c5d7a5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_9ab345e4-76b9-4b94-865d-c1819b7f32d6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_f7de3f6c-43f2-4190-89ba-f16c00c5d7a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SubsidiariesMember_a91b6b9a-4be4-4446-8967-3c9e5affab12" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_f7de3f6c-43f2-4190-89ba-f16c00c5d7a5" xlink:to="loc_srt_SubsidiariesMember_a91b6b9a-4be4-4446-8967-3c9e5affab12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_b650d8f5-0d64-4f9a-9622-5f4fd058b5ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_19e6852e-31c3-4a87-81b2-5d94185fe590" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_b650d8f5-0d64-4f9a-9622-5f4fd058b5ec" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#LongTermDebtandOtherCreditFacilitiesScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_eab4e35d-1074-41e2-9a0b-326260aa84c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:to="loc_us-gaap_DebtInstrumentTable_eab4e35d-1074-41e2-9a0b-326260aa84c7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_e12f668c-32ef-41c5-8a35-3687c8ae2529" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_eab4e35d-1074-41e2-9a0b-326260aa84c7" xlink:to="loc_us-gaap_DebtInstrumentAxis_e12f668c-32ef-41c5-8a35-3687c8ae2529" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_e12f668c-32ef-41c5-8a35-3687c8ae2529_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_e12f668c-32ef-41c5-8a35-3687c8ae2529" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_e12f668c-32ef-41c5-8a35-3687c8ae2529_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_e12f668c-32ef-41c5-8a35-3687c8ae2529" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB1FacilityMember_df683d4e-9dda-4514-bf59-db66dbf145bc" xlink:href="tln-20260331.xsd#tln_TLB1FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:to="loc_tln_TLB1FacilityMember_df683d4e-9dda-4514-bf59-db66dbf145bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB2FacilityMember_3d828e72-5877-4c97-aaf8-16c5c507faa8" xlink:href="tln-20260331.xsd#tln_TLB2FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:to="loc_tln_TLB2FacilityMember_3d828e72-5877-4c97-aaf8-16c5c507faa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_TLB3FacilityMember_019bd829-4c96-7046-a034-39a38b8a9b7e" xlink:href="tln-20260331.xsd#tln_TLB3FacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:to="loc_tln_TLB3FacilityMember_019bd829-4c96-7046-a034-39a38b8a9b7e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.25SeniorUnsecuredNotesDue2034Member_019c9034-ba61-792a-9032-707648bd15b7" xlink:href="tln-20260331.xsd#tln_A6.25SeniorUnsecuredNotesDue2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:to="loc_tln_A6.25SeniorUnsecuredNotesDue2034Member_019c9034-ba61-792a-9032-707648bd15b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.50SeniorUnsecuredNotesDue2036Member_019c9036-971e-7683-86f1-9a91525a913c" xlink:href="tln-20260331.xsd#tln_A6.50SeniorUnsecuredNotesDue2036Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:to="loc_tln_A6.50SeniorUnsecuredNotesDue2036Member_019c9036-971e-7683-86f1-9a91525a913c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PEDFA2009BBondsMember_9a82535b-aa00-4e64-b822-224b8d90d005" xlink:href="tln-20260331.xsd#tln_PEDFA2009BBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:to="loc_tln_PEDFA2009BBondsMember_9a82535b-aa00-4e64-b822-224b8d90d005" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PEDFA2009CBondsMember_6d76b1be-e2ca-455e-8daf-1a292c890af0" xlink:href="tln-20260331.xsd#tln_PEDFA2009CBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_23085c9d-0ab9-44b3-806c-8dfd19b5cf0f" xlink:to="loc_tln_PEDFA2009CBondsMember_6d76b1be-e2ca-455e-8daf-1a292c890af0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_224d5d85-b4d3-40d4-bb19-5b003654c4bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_eab4e35d-1074-41e2-9a0b-326260aa84c7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_224d5d85-b4d3-40d4-bb19-5b003654c4bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_224d5d85-b4d3-40d4-bb19-5b003654c4bf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_224d5d85-b4d3-40d4-bb19-5b003654c4bf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_224d5d85-b4d3-40d4-bb19-5b003654c4bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_36eadb02-61f1-4080-a38b-24b3238b816e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_224d5d85-b4d3-40d4-bb19-5b003654c4bf" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_36eadb02-61f1-4080-a38b-24b3238b816e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_1384c135-16b3-413b-8c96-8f0586bbeb65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_36eadb02-61f1-4080-a38b-24b3238b816e" xlink:to="loc_us-gaap_SecuredDebtMember_1384c135-16b3-413b-8c96-8f0586bbeb65" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SecuredNotesMember_46ce0f5e-011f-4fbb-b51e-84d5483fac66" xlink:href="tln-20260331.xsd#tln_SecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_36eadb02-61f1-4080-a38b-24b3238b816e" xlink:to="loc_tln_SecuredNotesMember_46ce0f5e-011f-4fbb-b51e-84d5483fac66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_019bd82d-d73a-785c-9f8a-f781a882a01b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_36eadb02-61f1-4080-a38b-24b3238b816e" xlink:to="loc_us-gaap_UnsecuredDebtMember_019bd82d-d73a-785c-9f8a-f781a882a01b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BondsMember_56f14b8a-d9eb-416c-b561-f5c8800ef9c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_36eadb02-61f1-4080-a38b-24b3238b816e" xlink:to="loc_us-gaap_BondsMember_56f14b8a-d9eb-416c-b561-f5c8800ef9c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_4aac6f7d-6af8-48e6-8e7f-2bbe66f6f404" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_4aac6f7d-6af8-48e6-8e7f-2bbe66f6f404" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_add9815e-5f34-487e-b9a7-c88dff46834b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_add9815e-5f34-487e-b9a7-c88dff46834b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_d436ea9f-3fd3-4412-8411-fe59b3f1e55b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_d436ea9f-3fd3-4412-8411-fe59b3f1e55b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_bf5f7cf7-6973-4350-8fd8-9b0f31af263e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:to="loc_us-gaap_LongTermDebt_bf5f7cf7-6973-4350-8fd8-9b0f31af263e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_2afb4876-889e-4c03-b945-014c6e24ebf2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:to="loc_us-gaap_LongTermDebtCurrent_2afb4876-889e-4c03-b945-014c6e24ebf2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_a9725be3-38c3-472f-b992-f3ccefbc14d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_3c2dafff-f1f7-48d3-b08b-1c15857994d6" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_a9725be3-38c3-472f-b992-f3ccefbc14d5" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofRevolvingCreditandOtherFacilitiesDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#LongTermDebtandOtherCreditFacilitiesScheduleofRevolvingCreditandOtherFacilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesScheduleofRevolvingCreditandOtherFacilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_22e3ae27-b4c8-465b-a934-cf1379d19e5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_45f2cc34-9801-4a70-b18a-1d65d788f35f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_22e3ae27-b4c8-465b-a934-cf1379d19e5c" xlink:to="loc_us-gaap_DebtInstrumentTable_45f2cc34-9801-4a70-b18a-1d65d788f35f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_b282b23e-6280-4c75-9dd0-8d3445dbb290" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_45f2cc34-9801-4a70-b18a-1d65d788f35f" xlink:to="loc_us-gaap_DebtInstrumentAxis_b282b23e-6280-4c75-9dd0-8d3445dbb290" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b282b23e-6280-4c75-9dd0-8d3445dbb290_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_b282b23e-6280-4c75-9dd0-8d3445dbb290" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b282b23e-6280-4c75-9dd0-8d3445dbb290_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5d4511c8-7e8e-46d5-8942-61fdff827e22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_b282b23e-6280-4c75-9dd0-8d3445dbb290" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5d4511c8-7e8e-46d5-8942-61fdff827e22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_70bcc1fb-37a1-4486-a0ef-c13c637eab67" xlink:href="tln-20260331.xsd#tln_SeniorSecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5d4511c8-7e8e-46d5-8942-61fdff827e22" xlink:to="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_70bcc1fb-37a1-4486-a0ef-c13c637eab67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_StandAloneLetterOfCreditFacilityMember_6aa097f5-f9a4-4eb9-a202-b4d27ffd5844" xlink:href="tln-20260331.xsd#tln_StandAloneLetterOfCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5d4511c8-7e8e-46d5-8942-61fdff827e22" xlink:to="loc_tln_StandAloneLetterOfCreditFacilityMember_6aa097f5-f9a4-4eb9-a202-b4d27ffd5844" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_0030569a-b3a3-432d-b350-6bfbddcafb38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_45f2cc34-9801-4a70-b18a-1d65d788f35f" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_0030569a-b3a3-432d-b350-6bfbddcafb38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_0030569a-b3a3-432d-b350-6bfbddcafb38_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_0030569a-b3a3-432d-b350-6bfbddcafb38" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_0030569a-b3a3-432d-b350-6bfbddcafb38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_94a54a32-9489-4699-ad40-f09fcefdea4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_0030569a-b3a3-432d-b350-6bfbddcafb38" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_94a54a32-9489-4699-ad40-f09fcefdea4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_7ff073a0-2f8c-4239-918b-f172dfd8ec9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_94a54a32-9489-4699-ad40-f09fcefdea4f" xlink:to="loc_us-gaap_LineOfCreditMember_7ff073a0-2f8c-4239-918b-f172dfd8ec9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_a9b3184f-b9db-46f2-a442-ccc678598fb6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_45f2cc34-9801-4a70-b18a-1d65d788f35f" xlink:to="loc_us-gaap_CreditFacilityAxis_a9b3184f-b9db-46f2-a442-ccc678598fb6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_a9b3184f-b9db-46f2-a442-ccc678598fb6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_a9b3184f-b9db-46f2-a442-ccc678598fb6" xlink:to="loc_us-gaap_CreditFacilityDomain_a9b3184f-b9db-46f2-a442-ccc678598fb6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6095634e-3312-4529-afa8-d90823a5fbbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_a9b3184f-b9db-46f2-a442-ccc678598fb6" xlink:to="loc_us-gaap_CreditFacilityDomain_6095634e-3312-4529-afa8-d90823a5fbbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_38261356-d933-40b7-b015-af851494407e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6095634e-3312-4529-afa8-d90823a5fbbe" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_38261356-d933-40b7-b015-af851494407e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_e6116dcf-db53-4dad-8347-bbd820f9b9ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6095634e-3312-4529-afa8-d90823a5fbbe" xlink:to="loc_us-gaap_LetterOfCreditMember_e6116dcf-db53-4dad-8347-bbd820f9b9ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_822a8f9b-dad5-4ee1-bdb1-d56fa2d9287b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_22e3ae27-b4c8-465b-a934-cf1379d19e5c" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_822a8f9b-dad5-4ee1-bdb1-d56fa2d9287b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_5091a15e-0ed9-434a-b16a-290a1f63122a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_22e3ae27-b4c8-465b-a934-cf1379d19e5c" xlink:to="loc_us-gaap_LineOfCredit_5091a15e-0ed9-434a-b16a-290a1f63122a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_71de636f-ada2-40b5-978a-15d48a247422" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_22e3ae27-b4c8-465b-a934-cf1379d19e5c" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_71de636f-ada2-40b5-978a-15d48a247422" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesNarrativeDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#LongTermDebtandOtherCreditFacilitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/LongTermDebtandOtherCreditFacilitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_304c3a2b-7a4c-4a2f-b743-9f130fb37343" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_DebtInstrumentTable_304c3a2b-7a4c-4a2f-b743-9f130fb37343" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019b2ac5-b32b-73d7-a32a-763b4c130d29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_304c3a2b-7a4c-4a2f-b743-9f130fb37343" xlink:to="loc_us-gaap_DebtInstrumentAxis_019b2ac5-b32b-73d7-a32a-763b4c130d29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-73d7-a32a-763b4c130d29_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b2ac5-b32b-73d7-a32a-763b4c130d29" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-73d7-a32a-763b4c130d29_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-7153-abf8-737728f79fcc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b2ac5-b32b-73d7-a32a-763b4c130d29" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-7153-abf8-737728f79fcc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.125SeniorUnsecuredNotesDue2031Member_019db0db-d100-790b-a040-53df71f05509" xlink:href="tln-20260331.xsd#tln_A6.125SeniorUnsecuredNotesDue2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-7153-abf8-737728f79fcc" xlink:to="loc_tln_A6.125SeniorUnsecuredNotesDue2031Member_019db0db-d100-790b-a040-53df71f05509" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_A6.375SeniorUnsecuredNotesDue2033Member_019db0dd-b8d5-7f1d-85bd-77752cc48fe3" xlink:href="tln-20260331.xsd#tln_A6.375SeniorUnsecuredNotesDue2033Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-7153-abf8-737728f79fcc" xlink:to="loc_tln_A6.375SeniorUnsecuredNotesDue2033Member_019db0dd-b8d5-7f1d-85bd-77752cc48fe3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_019dd36d-bd9f-7413-8bee-556b9c6b9e35" xlink:href="tln-20260331.xsd#tln_SeniorSecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-7153-abf8-737728f79fcc" xlink:to="loc_tln_SeniorSecuredRevolvingCreditFacilityMember_019dd36d-bd9f-7413-8bee-556b9c6b9e35" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_StandAloneLetterOfCreditFacilityMember_019dd49a-a88c-7bfc-92a8-46209d32289d" xlink:href="tln-20260331.xsd#tln_StandAloneLetterOfCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b2ac5-b32b-7153-abf8-737728f79fcc" xlink:to="loc_tln_StandAloneLetterOfCreditFacilityMember_019dd49a-a88c-7bfc-92a8-46209d32289d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019b2ac5-b32b-7cbd-8c86-961e2eca4649" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_304c3a2b-7a4c-4a2f-b743-9f130fb37343" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019b2ac5-b32b-7cbd-8c86-961e2eca4649" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-7cbd-8c86-961e2eca4649_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b2ac5-b32b-7cbd-8c86-961e2eca4649" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-7cbd-8c86-961e2eca4649_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-778d-a205-72599cb900c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b2ac5-b32b-7cbd-8c86-961e2eca4649" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-778d-a205-72599cb900c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_019db0da-146c-76c6-8920-063528a1ce68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-778d-a205-72599cb900c5" xlink:to="loc_us-gaap_UnsecuredDebtMember_019db0da-146c-76c6-8920-063528a1ce68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019d2590-a081-7073-a5ce-90114a361060" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-778d-a205-72599cb900c5" xlink:to="loc_us-gaap_SecuredDebtMember_019d2590-a081-7073-a5ce-90114a361060" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019dc29f-dc6e-7db5-b88b-682c3cc46061" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-778d-a205-72599cb900c5" xlink:to="loc_us-gaap_LineOfCreditMember_019dc29f-dc6e-7db5-b88b-682c3cc46061" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019dba64-6c4e-796e-a9a5-dc9767db276d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b2ac5-b32b-778d-a205-72599cb900c5" xlink:to="loc_us-gaap_LetterOfCreditMember_019dba64-6c4e-796e-a9a5-dc9767db276d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019db0dc-d7df-7f25-a6dd-cb0810280e4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_304c3a2b-7a4c-4a2f-b743-9f130fb37343" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019db0dc-d7df-7f25-a6dd-cb0810280e4b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019db0dc-d7df-7f25-a6dd-cb0810280e4b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019db0dc-d7df-7f25-a6dd-cb0810280e4b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019db0dc-d7df-7f25-a6dd-cb0810280e4b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019db0dc-d7df-7079-95b5-5e05686f15b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019db0dc-d7df-7f25-a6dd-cb0810280e4b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019db0dc-d7df-7079-95b5-5e05686f15b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019db0dc-fb58-784c-a631-612ade6d0260" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019db0dc-d7df-7079-95b5-5e05686f15b7" xlink:to="loc_us-gaap_SubsequentEventMember_019db0dc-fb58-784c-a631-612ade6d0260" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019df440-648f-7d99-b474-ebc3b0c01439" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_304c3a2b-7a4c-4a2f-b743-9f130fb37343" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019df440-648f-7d99-b474-ebc3b0c01439" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019df440-648f-7d99-b474-ebc3b0c01439_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019df440-648f-7d99-b474-ebc3b0c01439" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019df440-648f-7d99-b474-ebc3b0c01439_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019df440-648f-75f9-948e-b475facc919c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019df440-648f-7d99-b474-ebc3b0c01439" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019df440-648f-75f9-948e-b475facc919c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_SecuredISDAsMember_019df440-648f-7e84-a881-43a8542e00b5" xlink:href="tln-20260331.xsd#tln_SecuredISDAsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019df440-648f-75f9-948e-b475facc919c" xlink:to="loc_tln_SecuredISDAsMember_019df440-648f-7e84-a881-43a8542e00b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019db0d8-f4f1-7bef-b814-74875d3a7ed1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019db0d8-f4f1-7bef-b814-74875d3a7ed1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019db0de-612b-740a-9e33-ddc471d5acdf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019db0de-612b-740a-9e33-ddc471d5acdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DebtInstrumentCovenantRedeemableAggregatePrincipalAmountContingentUponAcquisitionClosing_019dd4b4-b76f-7f21-947a-93d673742d1e" xlink:href="tln-20260331.xsd#tln_DebtInstrumentCovenantRedeemableAggregatePrincipalAmountContingentUponAcquisitionClosing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_tln_DebtInstrumentCovenantRedeemableAggregatePrincipalAmountContingentUponAcquisitionClosing_019dd4b4-b76f-7f21-947a-93d673742d1e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019ddf89-86be-767f-8923-a009ecd3e0de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019ddf89-86be-767f-8923-a009ecd3e0de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_019dd9bb-6bef-718a-80af-7e3aa2be034c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_019dd9bb-6bef-718a-80af-7e3aa2be034c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019df370-df7a-751f-b8c6-d76a19872564" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019df370-df7a-751f-b8c6-d76a19872564" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019dc29f-dc6e-7cd5-a574-8ad906ae623c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019dc29f-dc6e-7cd5-a574-8ad906ae623c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019df440-648f-7fc2-9041-bc0ea0bbca3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b2ac5-b32b-7eb1-bebd-f54a599d0853" xlink:to="loc_us-gaap_DerivativeAssetFairValueAfterOffsetAndDeductionSubjectToMasterNettingArrangement_019df440-648f-7fc2-9041-bc0ea0bbca3f" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/FairValueScheduleofRecurringFairValueMeasurementsDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#FairValueScheduleofRecurringFairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/FairValueScheduleofRecurringFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_652e5383-0bed-4777-b9c7-e3cd473400a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_11570919-8638-46c1-9ad9-77977dc4b6c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_652e5383-0bed-4777-b9c7-e3cd473400a5" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_11570919-8638-46c1-9ad9-77977dc4b6c7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c5c3b48-9e08-441e-a60e-0c3aef3ece43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_11570919-8638-46c1-9ad9-77977dc4b6c7" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c5c3b48-9e08-441e-a60e-0c3aef3ece43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5c5c3b48-9e08-441e-a60e-0c3aef3ece43_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c5c3b48-9e08-441e-a60e-0c3aef3ece43" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_5c5c3b48-9e08-441e-a60e-0c3aef3ece43_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_81fab3c3-e6a4-435d-8f09-44896b127bab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_5c5c3b48-9e08-441e-a60e-0c3aef3ece43" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_81fab3c3-e6a4-435d-8f09-44896b127bab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_f47199da-53e0-4b57-a239-c82d9b664efb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_81fab3c3-e6a4-435d-8f09-44896b127bab" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_f47199da-53e0-4b57-a239-c82d9b664efb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_30b72b47-1587-4349-ae1a-b73732f59952" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_81fab3c3-e6a4-435d-8f09-44896b127bab" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_30b72b47-1587-4349-ae1a-b73732f59952" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_aaec10c7-7180-4038-a6b5-e3ee3fa9aba5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_81fab3c3-e6a4-435d-8f09-44896b127bab" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_aaec10c7-7180-4038-a6b5-e3ee3fa9aba5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_824a2005-f6de-4b57-8126-2c72968d4679" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_11570919-8638-46c1-9ad9-77977dc4b6c7" xlink:to="loc_us-gaap_FinancialInstrumentAxis_824a2005-f6de-4b57-8126-2c72968d4679" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_824a2005-f6de-4b57-8126-2c72968d4679_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_824a2005-f6de-4b57-8126-2c72968d4679" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_824a2005-f6de-4b57-8126-2c72968d4679_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cbd10736-047d-4ba7-9118-0574f6d71ea1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_824a2005-f6de-4b57-8126-2c72968d4679" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cbd10736-047d-4ba7-9118-0574f6d71ea1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_f3fb8464-0c88-4672-8f79-759bfb19c45b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cbd10736-047d-4ba7-9118-0574f6d71ea1" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_f3fb8464-0c88-4672-8f79-759bfb19c45b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_264a656c-2523-4530-8f1a-2880a7ec9cd0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cbd10736-047d-4ba7-9118-0574f6d71ea1" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_264a656c-2523-4530-8f1a-2880a7ec9cd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_ad1f038d-05be-4c7d-b965-97522607cf9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_cbd10736-047d-4ba7-9118-0574f6d71ea1" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_ad1f038d-05be-4c7d-b965-97522607cf9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_24fe8507-1e2e-4fe3-b20e-2ccde42baabf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_11570919-8638-46c1-9ad9-77977dc4b6c7" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_24fe8507-1e2e-4fe3-b20e-2ccde42baabf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_24fe8507-1e2e-4fe3-b20e-2ccde42baabf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_24fe8507-1e2e-4fe3-b20e-2ccde42baabf" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_24fe8507-1e2e-4fe3-b20e-2ccde42baabf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2f7b6b7a-618a-4da8-b346-5847b86ea49f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_24fe8507-1e2e-4fe3-b20e-2ccde42baabf" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2f7b6b7a-618a-4da8-b346-5847b86ea49f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_115cc8f1-4211-4612-a780-4d2c05e54711" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2f7b6b7a-618a-4da8-b346-5847b86ea49f" xlink:to="loc_us-gaap_CommodityContractMember_115cc8f1-4211-4612-a780-4d2c05e54711" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_b0364a2f-17fe-4636-9a6a-51f10f91b70f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_2f7b6b7a-618a-4da8-b346-5847b86ea49f" xlink:to="loc_us-gaap_InterestRateContractMember_b0364a2f-17fe-4636-9a6a-51f10f91b70f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_652e5383-0bed-4777-b9c7-e3cd473400a5" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_30ba9168-bec1-4651-b789-973637148f27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_30ba9168-bec1-4651-b789-973637148f27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_c57f44ff-68dd-4cdc-b884-6701f496cfe7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_c57f44ff-68dd-4cdc-b884-6701f496cfe7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_a20d1509-1a8f-488f-be7d-88d6b96c5b80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_a20d1509-1a8f-488f-be7d-88d6b96c5b80" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReceivablesPayablesNetFairValue_8c19588a-7211-4b86-a84a-8b7682730edc" xlink:href="tln-20260331.xsd#tln_ReceivablesPayablesNetFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_tln_ReceivablesPayablesNetFairValue_8c19588a-7211-4b86-a84a-8b7682730edc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecommissioningTrustAssetsAmount_95983cfd-3a9c-4be0-a52e-ebb110568958" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DecommissioningTrustAssetsAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_DecommissioningTrustAssetsAmount_95983cfd-3a9c-4be0-a52e-ebb110568958" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_9b1a8b50-c1ec-4a4a-8b98-c19b6357c61d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_9b1a8b50-c1ec-4a4a-8b98-c19b6357c61d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_c6f7a7d0-6340-4ae0-9718-dc2bd821eac8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_c6f7a7d0-6340-4ae0-9718-dc2bd821eac8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_8be3a6b8-6ded-4427-bf01-2a138138a6b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_DerivativeAssets_8be3a6b8-6ded-4427-bf01-2a138138a6b9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_fe762330-3dee-4f6e-9d26-6a8f4aae9a56" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_143eb89c-e283-4057-a540-832586741779" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_fe762330-3dee-4f6e-9d26-6a8f4aae9a56" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_adcabb67-c30e-451b-bab9-8cf6e21b8bfc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_652e5383-0bed-4777-b9c7-e3cd473400a5" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_adcabb67-c30e-451b-bab9-8cf6e21b8bfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_bf01838a-1bae-4a25-8ecb-89a3cd90f847" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_adcabb67-c30e-451b-bab9-8cf6e21b8bfc" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_bf01838a-1bae-4a25-8ecb-89a3cd90f847" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_8c8570aa-0d3e-4774-a53e-d604ad6c5cf5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_adcabb67-c30e-451b-bab9-8cf6e21b8bfc" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_8c8570aa-0d3e-4774-a53e-d604ad6c5cf5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_d35f941d-2c8b-458d-b2e1-7b15c6d15fd9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_adcabb67-c30e-451b-bab9-8cf6e21b8bfc" xlink:to="loc_us-gaap_DerivativeLiabilities_d35f941d-2c8b-458d-b2e1-7b15c6d15fd9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_c4608c29-6586-4dc1-8c6e-3e1dbacc6f39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_adcabb67-c30e-451b-bab9-8cf6e21b8bfc" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_c4608c29-6586-4dc1-8c6e-3e1dbacc6f39" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#StockBasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16b3883-3461-4ecd-a335-a100adf04048" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6a66d2bb-b61c-4f38-9999-b83a184c77c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16b3883-3461-4ecd-a335-a100adf04048" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6a66d2bb-b61c-4f38-9999-b83a184c77c1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_93f3b87f-64d5-4ad6-9264-bb21a654dce7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6a66d2bb-b61c-4f38-9999-b83a184c77c1" xlink:to="loc_us-gaap_AwardTypeAxis_93f3b87f-64d5-4ad6-9264-bb21a654dce7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93f3b87f-64d5-4ad6-9264-bb21a654dce7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_93f3b87f-64d5-4ad6-9264-bb21a654dce7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93f3b87f-64d5-4ad6-9264-bb21a654dce7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a5385dbb-5e60-4b02-b1f7-d8e0d9282449" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_93f3b87f-64d5-4ad6-9264-bb21a654dce7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a5385dbb-5e60-4b02-b1f7-d8e0d9282449" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_f60c5e30-22ce-4840-ae7a-ffae0d77025b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a5385dbb-5e60-4b02-b1f7-d8e0d9282449" xlink:to="loc_us-gaap_PerformanceSharesMember_f60c5e30-22ce-4840-ae7a-ffae0d77025b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_5cdc5cf5-0299-417d-aa2d-ba780aedacee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a5385dbb-5e60-4b02-b1f7-d8e0d9282449" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_5cdc5cf5-0299-417d-aa2d-ba780aedacee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_019c6c44-132b-7c2a-b2ec-1e55baa09b25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6a66d2bb-b61c-4f38-9999-b83a184c77c1" xlink:to="loc_us-gaap_VestingAxis_019c6c44-132b-7c2a-b2ec-1e55baa09b25" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019c6c44-132b-7c2a-b2ec-1e55baa09b25_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_019c6c44-132b-7c2a-b2ec-1e55baa09b25" xlink:to="loc_us-gaap_VestingDomain_019c6c44-132b-7c2a-b2ec-1e55baa09b25_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019c6c44-132b-7ffc-a8a0-86a087796ffd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_019c6c44-132b-7c2a-b2ec-1e55baa09b25" xlink:to="loc_us-gaap_VestingDomain_019c6c44-132b-7ffc-a8a0-86a087796ffd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CliffVestingScheduleMember_019c6c44-132b-76f0-8b3d-c21676cc81ca" xlink:href="tln-20260331.xsd#tln_CliffVestingScheduleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019c6c44-132b-7ffc-a8a0-86a087796ffd" xlink:to="loc_tln_CliffVestingScheduleMember_019c6c44-132b-76f0-8b3d-c21676cc81ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_RatableVestingScheduleMember_019c6c44-132b-7d75-a547-907332d6ff29" xlink:href="tln-20260331.xsd#tln_RatableVestingScheduleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019c6c44-132b-7ffc-a8a0-86a087796ffd" xlink:to="loc_tln_RatableVestingScheduleMember_019c6c44-132b-7d75-a547-907332d6ff29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019c96cc-b1a9-7e8d-b6bf-995232f910d6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6a66d2bb-b61c-4f38-9999-b83a184c77c1" xlink:to="loc_srt_RangeAxis_019c96cc-b1a9-7e8d-b6bf-995232f910d6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019c96cc-b1a9-7e8d-b6bf-995232f910d6_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019c96cc-b1a9-7e8d-b6bf-995232f910d6" xlink:to="loc_srt_RangeMember_019c96cc-b1a9-7e8d-b6bf-995232f910d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019c96cc-b1a9-7e24-ae81-8e500d3c037b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019c96cc-b1a9-7e8d-b6bf-995232f910d6" xlink:to="loc_srt_RangeMember_019c96cc-b1a9-7e24-ae81-8e500d3c037b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019c96cc-ca15-7106-a3ca-9949fad003f5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019c96cc-b1a9-7e24-ae81-8e500d3c037b" xlink:to="loc_srt_MinimumMember_019c96cc-ca15-7106-a3ca-9949fad003f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019c96cc-f649-7c60-a574-b3139e06dd6f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019c96cc-b1a9-7e24-ae81-8e500d3c037b" xlink:to="loc_srt_MaximumMember_019c96cc-f649-7c60-a574-b3139e06dd6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_c274e552-f05d-4067-a47f-98bb27ac0de6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16b3883-3461-4ecd-a335-a100adf04048" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_c274e552-f05d-4067-a47f-98bb27ac0de6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019c6c44-132b-7824-96f4-079ab5f49730" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16b3883-3461-4ecd-a335-a100adf04048" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019c6c44-132b-7824-96f4-079ab5f49730" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CashSettlementPercentage_019c7774-3762-7d72-aef1-1d4ec48b8380" xlink:href="tln-20260331.xsd#tln_CashSettlementPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16b3883-3461-4ecd-a335-a100adf04048" xlink:to="loc_tln_CashSettlementPercentage_019c7774-3762-7d72-aef1-1d4ec48b8380" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent_019c2eb9-3eaa-765b-881f-02332be0680f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16b3883-3461-4ecd-a335-a100adf04048" xlink:to="loc_us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent_019c2eb9-3eaa-765b-881f-02332be0680f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_019c4750-c934-7c85-8676-0dc15a106faa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f16b3883-3461-4ecd-a335-a100adf04048" xlink:to="loc_us-gaap_SharePrice_019c4750-c934-7c85-8676-0dc15a106faa" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofNonvestedPerformanceStockUnitsandRestrictedStockUnitsDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#StockBasedCompensationScheduleofNonvestedPerformanceStockUnitsandRestrictedStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofNonvestedPerformanceStockUnitsandRestrictedStockUnitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_328e0393-54c3-458a-a0dc-5dd303bc8c80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9e13c648-5c9c-42b0-83a3-4e88fa4638a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_328e0393-54c3-458a-a0dc-5dd303bc8c80" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9e13c648-5c9c-42b0-83a3-4e88fa4638a5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_14c6f8cb-3d09-4b97-84c2-5770bac9eefd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9e13c648-5c9c-42b0-83a3-4e88fa4638a5" xlink:to="loc_us-gaap_AwardTypeAxis_14c6f8cb-3d09-4b97-84c2-5770bac9eefd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_14c6f8cb-3d09-4b97-84c2-5770bac9eefd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_14c6f8cb-3d09-4b97-84c2-5770bac9eefd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_14c6f8cb-3d09-4b97-84c2-5770bac9eefd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_27d5fcbc-356b-45c6-a739-1159d9a81905" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_14c6f8cb-3d09-4b97-84c2-5770bac9eefd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_27d5fcbc-356b-45c6-a739-1159d9a81905" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_71f32973-2b3b-4705-8264-afcbbcd00be0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_27d5fcbc-356b-45c6-a739-1159d9a81905" xlink:to="loc_us-gaap_PerformanceSharesMember_71f32973-2b3b-4705-8264-afcbbcd00be0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedPerformanceSharesMember_019c6094-ebf8-73b1-a64e-d5f5577b02c9" xlink:href="tln-20260331.xsd#tln_LiabilityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PerformanceSharesMember_71f32973-2b3b-4705-8264-afcbbcd00be0" xlink:to="loc_tln_LiabilityClassifiedPerformanceSharesMember_019c6094-ebf8-73b1-a64e-d5f5577b02c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedPerformanceSharesMember_019c6094-9a47-79f2-8ed1-9b478a8e7553" xlink:href="tln-20260331.xsd#tln_EquityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PerformanceSharesMember_71f32973-2b3b-4705-8264-afcbbcd00be0" xlink:to="loc_tln_EquityClassifiedPerformanceSharesMember_019c6094-9a47-79f2-8ed1-9b478a8e7553" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_afc84f10-0a70-4b1b-ac71-a92045f58545" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_27d5fcbc-356b-45c6-a739-1159d9a81905" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_afc84f10-0a70-4b1b-ac71-a92045f58545" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019c608a-5182-7c4c-8e6a-614ace0f5503" xlink:href="tln-20260331.xsd#tln_LiabilityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedStockUnitsRSUMember_afc84f10-0a70-4b1b-ac71-a92045f58545" xlink:to="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019c608a-5182-7c4c-8e6a-614ace0f5503" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019c6089-afb3-79c1-aa5d-280886ae1518" xlink:href="tln-20260331.xsd#tln_EquityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedStockUnitsRSUMember_afc84f10-0a70-4b1b-ac71-a92045f58545" xlink:to="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019c6089-afb3-79c1-aa5d-280886ae1518" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_35811ab4-c5b5-4359-bb9a-b87a89c36a3d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9e13c648-5c9c-42b0-83a3-4e88fa4638a5" xlink:to="loc_srt_RangeAxis_35811ab4-c5b5-4359-bb9a-b87a89c36a3d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_35811ab4-c5b5-4359-bb9a-b87a89c36a3d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_35811ab4-c5b5-4359-bb9a-b87a89c36a3d" xlink:to="loc_srt_RangeMember_35811ab4-c5b5-4359-bb9a-b87a89c36a3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_19c3e505-0391-4495-bf41-66b86b692844" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_35811ab4-c5b5-4359-bb9a-b87a89c36a3d" xlink:to="loc_srt_RangeMember_19c3e505-0391-4495-bf41-66b86b692844" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_24d3ee30-607a-4c45-8210-007dd3b4475c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_19c3e505-0391-4495-bf41-66b86b692844" xlink:to="loc_srt_MinimumMember_24d3ee30-607a-4c45-8210-007dd3b4475c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_0460269c-b203-484b-a9a0-990fa7793706" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_19c3e505-0391-4495-bf41-66b86b692844" xlink:to="loc_srt_MaximumMember_0460269c-b203-484b-a9a0-990fa7793706" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_89bd5ef8-a823-4371-9a49-9ca6e815b326" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_328e0393-54c3-458a-a0dc-5dd303bc8c80" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_89bd5ef8-a823-4371-9a49-9ca6e815b326" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d3554423-9b60-4869-be50-c367af71535e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_89bd5ef8-a823-4371-9a49-9ca6e815b326" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d3554423-9b60-4869-be50-c367af71535e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_2009fa6a-9ec5-4b73-99f6-662710451e83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_89bd5ef8-a823-4371-9a49-9ca6e815b326" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_2009fa6a-9ec5-4b73-99f6-662710451e83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_fa29b7b2-c6d9-4bdc-b8cb-7ed085fd1ba4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_3c90d780-f283-4590-9a21-78eeceb6c978" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_328e0393-54c3-458a-a0dc-5dd303bc8c80" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_3c90d780-f283-4590-9a21-78eeceb6c978" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_0cf695b1-dba8-40d7-a917-2a7713311b45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_3c90d780-f283-4590-9a21-78eeceb6c978" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_0cf695b1-dba8-40d7-a917-2a7713311b45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_fe224bc6-adbb-4093-9b21-97b6a8c9b580" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_3c90d780-f283-4590-9a21-78eeceb6c978" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_fe224bc6-adbb-4093-9b21-97b6a8c9b580" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_388192a5-fcb0-4445-9f68-25156a8b776d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsActualAmountOfAwardsEarnedPercentage_019c944c-ddde-73ea-ba1a-affeec7c941f" xlink:href="tln-20260331.xsd#tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsActualAmountOfAwardsEarnedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_328e0393-54c3-458a-a0dc-5dd303bc8c80" xlink:to="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsActualAmountOfAwardsEarnedPercentage_019c944c-ddde-73ea-ba1a-affeec7c941f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedBasedOnStockPricePerformanceNumber_019c944c-ddde-73ff-94af-d9c20aae3457" xlink:href="tln-20260331.xsd#tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedBasedOnStockPricePerformanceNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_328e0393-54c3-458a-a0dc-5dd303bc8c80" xlink:to="loc_tln_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedBasedOnStockPricePerformanceNumber_019c944c-ddde-73ff-94af-d9c20aae3457" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofSignificantInputsandAssumptionsofFairValueDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#StockBasedCompensationScheduleofSignificantInputsandAssumptionsofFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofSignificantInputsandAssumptionsofFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_238ec18e-714d-4e74-b483-8db9d7558071" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_efa0081d-466e-4c90-b493-8d87162edefb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_238ec18e-714d-4e74-b483-8db9d7558071" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_efa0081d-466e-4c90-b493-8d87162edefb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_61c551e5-235e-49f4-8347-82b4be4c071f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_efa0081d-466e-4c90-b493-8d87162edefb" xlink:to="loc_us-gaap_AwardTypeAxis_61c551e5-235e-49f4-8347-82b4be4c071f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61c551e5-235e-49f4-8347-82b4be4c071f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_61c551e5-235e-49f4-8347-82b4be4c071f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_61c551e5-235e-49f4-8347-82b4be4c071f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d7bd93e8-7d58-4aa4-9f09-eeb4997bf8d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_61c551e5-235e-49f4-8347-82b4be4c071f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d7bd93e8-7d58-4aa4-9f09-eeb4997bf8d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_6832ba6b-c12d-464c-8c7a-22449d6998d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d7bd93e8-7d58-4aa4-9f09-eeb4997bf8d3" xlink:to="loc_us-gaap_PerformanceSharesMember_6832ba6b-c12d-464c-8c7a-22449d6998d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_25bb7177-b3d4-4518-b16d-f1b61b9151dc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_efa0081d-466e-4c90-b493-8d87162edefb" xlink:to="loc_srt_RangeAxis_25bb7177-b3d4-4518-b16d-f1b61b9151dc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_25bb7177-b3d4-4518-b16d-f1b61b9151dc_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_25bb7177-b3d4-4518-b16d-f1b61b9151dc" xlink:to="loc_srt_RangeMember_25bb7177-b3d4-4518-b16d-f1b61b9151dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e7632e73-a97c-4e05-be42-81db288d1681" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_25bb7177-b3d4-4518-b16d-f1b61b9151dc" xlink:to="loc_srt_RangeMember_e7632e73-a97c-4e05-be42-81db288d1681" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_0f484e1a-ef59-48bb-9ec0-d2a85d4a8d90" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e7632e73-a97c-4e05-be42-81db288d1681" xlink:to="loc_srt_MinimumMember_0f484e1a-ef59-48bb-9ec0-d2a85d4a8d90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_5d5600ca-e469-460b-b774-f81265143ec9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e7632e73-a97c-4e05-be42-81db288d1681" xlink:to="loc_srt_MaximumMember_5d5600ca-e469-460b-b774-f81265143ec9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_c172834f-5a14-4731-863e-509e386d1d40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_238ec18e-714d-4e74-b483-8db9d7558071" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_c172834f-5a14-4731-863e-509e386d1d40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_e41073c7-016a-4e75-9ff7-dca20ca96a95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_238ec18e-714d-4e74-b483-8db9d7558071" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_e41073c7-016a-4e75-9ff7-dca20ca96a95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_f489dca4-7b91-469d-91c2-1336a4fec1f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_238ec18e-714d-4e74-b483-8db9d7558071" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_f489dca4-7b91-469d-91c2-1336a4fec1f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_2176f3c2-a831-4582-973a-defed48dd25c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_238ec18e-714d-4e74-b483-8db9d7558071" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_2176f3c2-a831-4582-973a-defed48dd25c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_3e4d1034-4e09-4093-b3ed-336c285ad271" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_238ec18e-714d-4e74-b483-8db9d7558071" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_3e4d1034-4e09-4093-b3ed-336c285ad271" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#StockBasedCompensationScheduleofStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofStockbasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c60a7-5a36-79d0-9362-3cfe9db4d8d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019c60a7-5a36-7f19-97a3-b45beb98de8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c60a7-5a36-79d0-9362-3cfe9db4d8d5" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019c60a7-5a36-7f19-97a3-b45beb98de8b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019c60a7-5a36-73db-859a-abeefe58c2f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019c60a7-5a36-7f19-97a3-b45beb98de8b" xlink:to="loc_us-gaap_AwardTypeAxis_019c60a7-5a36-73db-859a-abeefe58c2f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c60a7-5a36-73db-859a-abeefe58c2f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019c60a7-5a36-73db-859a-abeefe58c2f0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c60a7-5a36-73db-859a-abeefe58c2f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c60a7-5a36-78e9-8b1f-530f325e1058" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019c60a7-5a36-73db-859a-abeefe58c2f0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c60a7-5a36-78e9-8b1f-530f325e1058" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedAwardsMember_019c60a7-5a36-7873-9aa6-0e9e7bfd1418" xlink:href="tln-20260331.xsd#tln_LiabilityClassifiedAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c60a7-5a36-78e9-8b1f-530f325e1058" xlink:to="loc_tln_LiabilityClassifiedAwardsMember_019c60a7-5a36-7873-9aa6-0e9e7bfd1418" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedAwardsMember_019c60a7-5a36-7561-819b-aea39f2dac56" xlink:href="tln-20260331.xsd#tln_EquityClassifiedAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c60a7-5a36-78e9-8b1f-530f325e1058" xlink:to="loc_tln_EquityClassifiedAwardsMember_019c60a7-5a36-7561-819b-aea39f2dac56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_cf78f544-0192-4d4c-b732-ee0d4cd690fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c60a7-5a36-79d0-9362-3cfe9db4d8d5" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_cf78f544-0192-4d4c-b732-ee0d4cd690fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_a415c86b-1f97-4c8b-be47-7ce9791bdfb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c60a7-5a36-79d0-9362-3cfe9db4d8d5" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_a415c86b-1f97-4c8b-be47-7ce9791bdfb1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_d59d8a66-e141-4405-a6da-2a0fa0b58b8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c60a7-5a36-79d0-9362-3cfe9db4d8d5" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_d59d8a66-e141-4405-a6da-2a0fa0b58b8f" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockBasedCompensationScheduleofUnrecognizedStockBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#StockBasedCompensationScheduleofUnrecognizedStockBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockBasedCompensationScheduleofUnrecognizedStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c6c8c-0ad7-7ea6-9242-9f1a67af06d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019c6c8c-0ad7-701a-8835-06504d611ae8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c6c8c-0ad7-7ea6-9242-9f1a67af06d0" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019c6c8c-0ad7-701a-8835-06504d611ae8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019c6c8c-0ad7-7afc-8d05-5a154258ab34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019c6c8c-0ad7-701a-8835-06504d611ae8" xlink:to="loc_us-gaap_AwardTypeAxis_019c6c8c-0ad7-7afc-8d05-5a154258ab34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7afc-8d05-5a154258ab34_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019c6c8c-0ad7-7afc-8d05-5a154258ab34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7afc-8d05-5a154258ab34_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7ac3-ad40-2b1a6caf6fa6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019c6c8c-0ad7-7afc-8d05-5a154258ab34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7ac3-ad40-2b1a6caf6fa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedPerformanceSharesMember_019c6d19-013a-79fc-b82f-3ea0fd6b18c4" xlink:href="tln-20260331.xsd#tln_EquityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7ac3-ad40-2b1a6caf6fa6" xlink:to="loc_tln_EquityClassifiedPerformanceSharesMember_019c6d19-013a-79fc-b82f-3ea0fd6b18c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedPerformanceSharesMember_019c6d19-013a-7361-aa15-1f22196859de" xlink:href="tln-20260331.xsd#tln_LiabilityClassifiedPerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7ac3-ad40-2b1a6caf6fa6" xlink:to="loc_tln_LiabilityClassifiedPerformanceSharesMember_019c6d19-013a-7361-aa15-1f22196859de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019c6d18-812f-75a5-9416-c41950412d53" xlink:href="tln-20260331.xsd#tln_EquityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7ac3-ad40-2b1a6caf6fa6" xlink:to="loc_tln_EquityClassifiedRestrictedStockUnitsMember_019c6d18-812f-75a5-9416-c41950412d53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019c6d18-812f-7430-9652-0764cd25eeb2" xlink:href="tln-20260331.xsd#tln_LiabilityClassifiedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019c6c8c-0ad7-7ac3-ad40-2b1a6caf6fa6" xlink:to="loc_tln_LiabilityClassifiedRestrictedStockUnitsMember_019c6d18-812f-7430-9652-0764cd25eeb2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019c7702-79a0-774d-9334-6695afb08feb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c6c8c-0ad7-7ea6-9242-9f1a67af06d0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019c7702-79a0-774d-9334-6695afb08feb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019c6c8c-0ad7-7084-9a4c-50a23e9669aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019c6c8c-0ad7-7ea6-9242-9f1a67af06d0" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019c6c8c-0ad7-7084-9a4c-50a23e9669aa" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/EarningsPerShareScheduleofEarningsPerShareDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#EarningsPerShareScheduleofEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/EarningsPerShareScheduleofEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedLineItems_1f3cb5a6-f30a-4ca1-b7d7-5089f5516dee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDilutedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_a774bb94-8c5c-42b6-a749-995eb21519db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_1f3cb5a6-f30a-4ca1-b7d7-5089f5516dee" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_a774bb94-8c5c-42b6-a749-995eb21519db" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_a402d959-c1f4-48ed-8b6f-0397dc5291e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_a774bb94-8c5c-42b6-a749-995eb21519db" xlink:to="loc_us-gaap_AwardTypeAxis_a402d959-c1f4-48ed-8b6f-0397dc5291e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a402d959-c1f4-48ed-8b6f-0397dc5291e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_a402d959-c1f4-48ed-8b6f-0397dc5291e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a402d959-c1f4-48ed-8b6f-0397dc5291e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c9b1de98-4d65-44bb-a00b-7323d8ac1eb7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_a402d959-c1f4-48ed-8b6f-0397dc5291e9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c9b1de98-4d65-44bb-a00b-7323d8ac1eb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_552ceaf7-b567-4590-ad8a-cd026fb56018" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c9b1de98-4d65-44bb-a00b-7323d8ac1eb7" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_552ceaf7-b567-4590-ad8a-cd026fb56018" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_95347cba-dd54-4bcb-9567-165d09ce9038" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c9b1de98-4d65-44bb-a00b-7323d8ac1eb7" xlink:to="loc_us-gaap_PerformanceSharesMember_95347cba-dd54-4bcb-9567-165d09ce9038" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_30bce796-158f-472c-aa19-fad68e9e4b48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_1f3cb5a6-f30a-4ca1-b7d7-5089f5516dee" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_30bce796-158f-472c-aa19-fad68e9e4b48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_2aeb67d3-92dd-4eec-bbfe-be1383c4c7a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_30bce796-158f-472c-aa19-fad68e9e4b48" xlink:to="loc_us-gaap_ProfitLoss_2aeb67d3-92dd-4eec-bbfe-be1383c4c7a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_489b05d3-3220-43e4-b6db-31fab62bda7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_1f3cb5a6-f30a-4ca1-b7d7-5089f5516dee" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_489b05d3-3220-43e4-b6db-31fab62bda7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_c12777e5-9c11-46a7-92d1-4674d6a0bb49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_489b05d3-3220-43e4-b6db-31fab62bda7f" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_c12777e5-9c11-46a7-92d1-4674d6a0bb49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_7fb644e3-f9a0-4f2d-abf7-a383579f5eef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_489b05d3-3220-43e4-b6db-31fab62bda7f" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_7fb644e3-f9a0-4f2d-abf7-a383579f5eef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_51a0f12f-3ead-44c4-bca1-1fd496279ceb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_489b05d3-3220-43e4-b6db-31fab62bda7f" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_51a0f12f-3ead-44c4-bca1-1fd496279ceb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_c5511e68-cedd-4a41-b66c-8cc10783f35e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_1f3cb5a6-f30a-4ca1-b7d7-5089f5516dee" xlink:to="loc_us-gaap_EarningsPerShareBasic_c5511e68-cedd-4a41-b66c-8cc10783f35e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_e7f4dbe1-1593-4c31-bfbc-e9dd92ecc909" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_1f3cb5a6-f30a-4ca1-b7d7-5089f5516dee" xlink:to="loc_us-gaap_EarningsPerShareDiluted_e7f4dbe1-1593-4c31-bfbc-e9dd92ecc909" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/EarningsPerShareNarrativeDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#EarningsPerShareNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/EarningsPerShareNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_1af82008-768b-4e1c-8fb5-b166218578ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_b5e75dc0-4a5a-490b-9f46-4884cda27500" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_1af82008-768b-4e1c-8fb5-b166218578ad" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_b5e75dc0-4a5a-490b-9f46-4884cda27500" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_eba720df-95a5-4af6-8c11-8b995c54ec54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_b5e75dc0-4a5a-490b-9f46-4884cda27500" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_eba720df-95a5-4af6-8c11-8b995c54ec54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_eba720df-95a5-4af6-8c11-8b995c54ec54_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_eba720df-95a5-4af6-8c11-8b995c54ec54" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_eba720df-95a5-4af6-8c11-8b995c54ec54_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_5bd03f4d-ff35-42c9-84f7-2cca8b35a25b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_eba720df-95a5-4af6-8c11-8b995c54ec54" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_5bd03f4d-ff35-42c9-84f7-2cca8b35a25b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PerformanceSharesTargetNotMetMember_019dd36b-206d-71b6-a0e2-7a883150764a" xlink:href="tln-20260331.xsd#tln_PerformanceSharesTargetNotMetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_5bd03f4d-ff35-42c9-84f7-2cca8b35a25b" xlink:to="loc_tln_PerformanceSharesTargetNotMetMember_019dd36b-206d-71b6-a0e2-7a883150764a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_27a267ac-e353-4a38-b88e-9bd174cf8190" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_5bd03f4d-ff35-42c9-84f7-2cca8b35a25b" xlink:to="loc_us-gaap_PerformanceSharesMember_27a267ac-e353-4a38-b88e-9bd174cf8190" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_03dbb46d-c6f6-4ea3-95a9-e904a70d9d88" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_5bd03f4d-ff35-42c9-84f7-2cca8b35a25b" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_03dbb46d-c6f6-4ea3-95a9-e904a70d9d88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019c2e9b-a528-745d-81a0-e0fff01ecb8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_1af82008-768b-4e1c-8fb5-b166218578ad" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019c2e9b-a528-745d-81a0-e0fff01ecb8a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockholdersEquityChangesinAOCIDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#StockholdersEquityChangesinAOCIDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockholdersEquityChangesinAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_368c292a-d6af-4eb8-89e2-199939e631f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_9f087f25-5e8b-4398-b65a-b928fc2cd8f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_368c292a-d6af-4eb8-89e2-199939e631f2" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_9f087f25-5e8b-4398-b65a-b928fc2cd8f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_2ec2a0d3-c116-4ba1-a911-83567093567c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_9f087f25-5e8b-4398-b65a-b928fc2cd8f8" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_2ec2a0d3-c116-4ba1-a911-83567093567c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2ec2a0d3-c116-4ba1-a911-83567093567c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2ec2a0d3-c116-4ba1-a911-83567093567c" xlink:to="loc_us-gaap_EquityComponentDomain_2ec2a0d3-c116-4ba1-a911-83567093567c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2c62f482-f350-42cf-adc3-418ad9e4ae0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2ec2a0d3-c116-4ba1-a911-83567093567c" xlink:to="loc_us-gaap_EquityComponentDomain_2c62f482-f350-42cf-adc3-418ad9e4ae0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_0f4f501b-1cb6-40b1-b9c6-755e8020b453" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_2c62f482-f350-42cf-adc3-418ad9e4ae0e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_0f4f501b-1cb6-40b1-b9c6-755e8020b453" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_13cf1511-e184-4cd0-b203-17646c47c934" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_368c292a-d6af-4eb8-89e2-199939e631f2" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_13cf1511-e184-4cd0-b203-17646c47c934" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_30dd541d-f981-4db9-91bc-f4aabbecdddd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_13cf1511-e184-4cd0-b203-17646c47c934" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_30dd541d-f981-4db9-91bc-f4aabbecdddd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_49eba3d5-acc3-44c9-bca8-c3a376b13f4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_13cf1511-e184-4cd0-b203-17646c47c934" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_49eba3d5-acc3-44c9-bca8-c3a376b13f4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_f9b31d8e-73c0-4040-af2e-f79124f77e05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_13cf1511-e184-4cd0-b203-17646c47c934" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_f9b31d8e-73c0-4040-af2e-f79124f77e05" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTax_b0110e65-5a65-49d5-b4be-bb96a92cce2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_13cf1511-e184-4cd0-b203-17646c47c934" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTax_b0110e65-5a65-49d5-b4be-bb96a92cce2b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_cc80a57d-4dee-46cb-a7b0-0d1133798936" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_13cf1511-e184-4cd0-b203-17646c47c934" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_cc80a57d-4dee-46cb-a7b0-0d1133798936" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_82a3240a-bd25-471a-b6b1-7eada04febb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/StockholdersEquityComponentsofAOCIDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#StockholdersEquityComponentsofAOCIDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/StockholdersEquityComponentsofAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_96d7ad34-ac39-420f-bd3b-e9aa48146625" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_5828f5c3-0277-4876-b1d1-91223fbfbf3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_96d7ad34-ac39-420f-bd3b-e9aa48146625" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_5828f5c3-0277-4876-b1d1-91223fbfbf3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_dc9b5aa9-99fa-4bcc-b27b-84cf688848a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_5828f5c3-0277-4876-b1d1-91223fbfbf3b" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_dc9b5aa9-99fa-4bcc-b27b-84cf688848a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_dc9b5aa9-99fa-4bcc-b27b-84cf688848a5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_dc9b5aa9-99fa-4bcc-b27b-84cf688848a5" xlink:to="loc_us-gaap_EquityComponentDomain_dc9b5aa9-99fa-4bcc-b27b-84cf688848a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_794a3501-f95f-4f19-93a0-ac162c23de25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_dc9b5aa9-99fa-4bcc-b27b-84cf688848a5" xlink:to="loc_us-gaap_EquityComponentDomain_794a3501-f95f-4f19-93a0-ac162c23de25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1bbca997-163a-48b6-95f1-1faf69431126" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_794a3501-f95f-4f19-93a0-ac162c23de25" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1bbca997-163a-48b6-95f1-1faf69431126" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_3e4d0905-bf5d-49bc-a5f3-60d12557ec0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1bbca997-163a-48b6-95f1-1faf69431126" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_3e4d0905-bf5d-49bc-a5f3-60d12557ec0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_7fd90968-65f4-4b57-b126-703312477d14" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1bbca997-163a-48b6-95f1-1faf69431126" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_7fd90968-65f4-4b57-b126-703312477d14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_f2b165a6-8c87-4422-afaf-5c4a183fe335" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1bbca997-163a-48b6-95f1-1faf69431126" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_f2b165a6-8c87-4422-afaf-5c4a183fe335" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_0802a51d-875f-475d-bafb-3b8261aca3fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_96d7ad34-ac39-420f-bd3b-e9aa48146625" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_0802a51d-875f-475d-bafb-3b8261aca3fe" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/AcquisitionsandDivestitures2026PendingAcquisitionsDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#AcquisitionsandDivestitures2026PendingAcquisitionsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/AcquisitionsandDivestitures2026PendingAcquisitionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionTable_019c6cb9-2835-7236-9c83-20dbefe525d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:to="loc_us-gaap_AssetAcquisitionTable_019c6cb9-2835-7236-9c83-20dbefe525d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019c7760-7ff8-7c6e-9943-f44182cdcdbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AssetAcquisitionTable_019c6cb9-2835-7236-9c83-20dbefe525d3" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019c7760-7ff8-7c6e-9943-f44182cdcdbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019c7760-7ff8-7c6e-9943-f44182cdcdbe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019c7760-7ff8-7c6e-9943-f44182cdcdbe" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019c7760-7ff8-7c6e-9943-f44182cdcdbe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019c7760-7ff8-7daa-b097-9320ce5716ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019c7760-7ff8-7c6e-9943-f44182cdcdbe" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019c7760-7ff8-7daa-b097-9320ce5716ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CornerstoneAcquisitionMember_019c6cb9-2835-727a-b3d6-34cce4371871" xlink:href="tln-20260331.xsd#tln_CornerstoneAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019c7760-7ff8-7daa-b097-9320ce5716ca" xlink:to="loc_tln_CornerstoneAcquisitionMember_019c6cb9-2835-727a-b3d6-34cce4371871" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PowerGenerationFacilityAxis_019c7766-d73f-7862-bd82-a4deab22f3a2" xlink:href="tln-20260331.xsd#tln_PowerGenerationFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AssetAcquisitionTable_019c6cb9-2835-7236-9c83-20dbefe525d3" xlink:to="loc_tln_PowerGenerationFacilityAxis_019c7766-d73f-7862-bd82-a4deab22f3a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PowerGenerationFacilityDomain_019c7766-d73f-7862-bd82-a4deab22f3a2_default" xlink:href="tln-20260331.xsd#tln_PowerGenerationFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_tln_PowerGenerationFacilityAxis_019c7766-d73f-7862-bd82-a4deab22f3a2" xlink:to="loc_tln_PowerGenerationFacilityDomain_019c7766-d73f-7862-bd82-a4deab22f3a2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PowerGenerationFacilityDomain_019c7766-d73f-723e-9af5-fa7ce29de035" xlink:href="tln-20260331.xsd#tln_PowerGenerationFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_tln_PowerGenerationFacilityAxis_019c7766-d73f-7862-bd82-a4deab22f3a2" xlink:to="loc_tln_PowerGenerationFacilityDomain_019c7766-d73f-723e-9af5-fa7ce29de035" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_LawrenceburgPowerPlantMember_019c6cb9-2835-7540-856f-64d97d292caf" xlink:href="tln-20260331.xsd#tln_LawrenceburgPowerPlantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_PowerGenerationFacilityDomain_019c7766-d73f-723e-9af5-fa7ce29de035" xlink:to="loc_tln_LawrenceburgPowerPlantMember_019c6cb9-2835-7540-856f-64d97d292caf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_WaterfordEnergyCenterMember_019c6cb9-2835-7066-b0d5-7704c2ad3f07" xlink:href="tln-20260331.xsd#tln_WaterfordEnergyCenterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_PowerGenerationFacilityDomain_019c7766-d73f-723e-9af5-fa7ce29de035" xlink:to="loc_tln_WaterfordEnergyCenterMember_019c6cb9-2835-7066-b0d5-7704c2ad3f07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DarbyGeneratingStationMember_019c6cb9-2835-769e-96ca-3f32220a36aa" xlink:href="tln-20260331.xsd#tln_DarbyGeneratingStationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_PowerGenerationFacilityDomain_019c7766-d73f-723e-9af5-fa7ce29de035" xlink:to="loc_tln_DarbyGeneratingStationMember_019c6cb9-2835-769e-96ca-3f32220a36aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019c96cb-d375-7931-bdac-e5aa0894ccfb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AssetAcquisitionTable_019c6cb9-2835-7236-9c83-20dbefe525d3" xlink:to="loc_srt_StatementScenarioAxis_019c96cb-d375-7931-bdac-e5aa0894ccfb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019c96cb-d375-7931-bdac-e5aa0894ccfb_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019c96cb-d375-7931-bdac-e5aa0894ccfb" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019c96cb-d375-7931-bdac-e5aa0894ccfb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019c96cb-d375-7ded-a8ee-a7d827075968" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019c96cb-d375-7931-bdac-e5aa0894ccfb" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019c96cb-d375-7ded-a8ee-a7d827075968" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019c96cb-d375-788e-bab4-b57a4fee99d8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_019c96cb-d375-7ded-a8ee-a7d827075968" xlink:to="loc_srt_ScenarioForecastMember_019c96cb-d375-788e-bab4-b57a4fee99d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PowerGeneratingCapacityOfNaturalGasFiredCombinedCycleGenerationPlant_019c6cb9-2835-7438-a812-2a8d599ef33d" xlink:href="tln-20260331.xsd#tln_PowerGeneratingCapacityOfNaturalGasFiredCombinedCycleGenerationPlant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:to="loc_tln_PowerGeneratingCapacityOfNaturalGasFiredCombinedCycleGenerationPlant_019c6cb9-2835-7438-a812-2a8d599ef33d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PowerGeneratingCapacityOfNaturalGasFiredCombustionTurbine_019c6cb9-2835-7df3-a7af-5ed3f16b9251" xlink:href="tln-20260331.xsd#tln_PowerGeneratingCapacityOfNaturalGasFiredCombustionTurbine"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:to="loc_tln_PowerGeneratingCapacityOfNaturalGasFiredCombustionTurbine_019c6cb9-2835-7df3-a7af-5ed3f16b9251" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019c7765-339a-722e-bd55-62fd6e9a8f15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019c7765-339a-722e-bd55-62fd6e9a8f15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019c7763-3e24-7fc1-ae3b-4ab3412a6c9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019c7763-3e24-7fc1-ae3b-4ab3412a6c9a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019c8e4d-7ad6-7c46-8105-e19e5032918d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019c8e4d-7ad6-7c46-8105-e19e5032918d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019c7764-ca96-7baa-a0d6-d8c2ae683a8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionLineItems_019c6cb9-2835-7748-8157-5b67090af4cd" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019c7764-ca96-7baa-a0d6-d8c2ae683a8e" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/SegmentsSegmentsandReconciliationDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#SegmentsSegmentsandReconciliationDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/SegmentsSegmentsandReconciliationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6ac0d84-d824-4267-b47a-552f95ed53d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6ac0d84-d824-4267-b47a-552f95ed53d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_4967da7a-46e9-419e-b041-d81fcce96bc1" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6ac0d84-d824-4267-b47a-552f95ed53d1" xlink:to="loc_srt_ConsolidationItemsAxis_4967da7a-46e9-419e-b041-d81fcce96bc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_4967da7a-46e9-419e-b041-d81fcce96bc1_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_4967da7a-46e9-419e-b041-d81fcce96bc1" xlink:to="loc_srt_ConsolidationItemsDomain_4967da7a-46e9-419e-b041-d81fcce96bc1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_bd940a12-a84c-4275-9d68-930b9600c05f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_4967da7a-46e9-419e-b041-d81fcce96bc1" xlink:to="loc_srt_ConsolidationItemsDomain_bd940a12-a84c-4275-9d68-930b9600c05f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_1b3e6b6c-eaaf-4324-bdc1-ed1ca8b4718c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_bd940a12-a84c-4275-9d68-930b9600c05f" xlink:to="loc_us-gaap_OperatingSegmentsMember_1b3e6b6c-eaaf-4324-bdc1-ed1ca8b4718c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CorporateAndEliminationsMember_90f84b9f-5819-41cd-80a4-3dc8e78a5716" xlink:href="tln-20260331.xsd#tln_CorporateAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_bd940a12-a84c-4275-9d68-930b9600c05f" xlink:to="loc_tln_CorporateAndEliminationsMember_90f84b9f-5819-41cd-80a4-3dc8e78a5716" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_4581aad8-c6b2-413b-9349-34da9555e6fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6ac0d84-d824-4267-b47a-552f95ed53d1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_4581aad8-c6b2-413b-9349-34da9555e6fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4581aad8-c6b2-413b-9349-34da9555e6fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_4581aad8-c6b2-413b-9349-34da9555e6fc" xlink:to="loc_us-gaap_SegmentDomain_4581aad8-c6b2-413b-9349-34da9555e6fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e18946d2-2654-4cd2-83cf-6bd09d3982da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_4581aad8-c6b2-413b-9349-34da9555e6fc" xlink:to="loc_us-gaap_SegmentDomain_e18946d2-2654-4cd2-83cf-6bd09d3982da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PJMSegmentMember_473c1389-ae7c-4da6-8a82-2bf95dcd9b90" xlink:href="tln-20260331.xsd#tln_PJMSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e18946d2-2654-4cd2-83cf-6bd09d3982da" xlink:to="loc_tln_PJMSegmentMember_473c1389-ae7c-4da6-8a82-2bf95dcd9b90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllOtherSegmentsMember_98c1ef4e-4623-4dd7-937a-5e7db77cd4ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllOtherSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e18946d2-2654-4cd2-83cf-6bd09d3982da" xlink:to="loc_us-gaap_AllOtherSegmentsMember_98c1ef4e-4623-4dd7-937a-5e7db77cd4ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_0c9774d7-da9e-44a1-b80e-be4e0cf6fba4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:to="loc_us-gaap_Revenues_0c9774d7-da9e-44a1-b80e-be4e0cf6fba4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperationMaintenanceAndDevelopmentExpense_cda2e0b6-a7d8-4d25-88c7-5182f1a83309" xlink:href="tln-20260331.xsd#tln_OperationMaintenanceAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:to="loc_tln_OperationMaintenanceAndDevelopmentExpense_cda2e0b6-a7d8-4d25-88c7-5182f1a83309" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDebtExpense_2b253de7-348d-4a34-8ea2-8d4372d65f26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestAndDebtExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:to="loc_us-gaap_InterestAndDebtExpense_2b253de7-348d-4a34-8ea2-8d4372d65f26" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_ac57bcd6-529d-4e91-8a49-3b9264e1d44e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_ac57bcd6-529d-4e91-8a49-3b9264e1d44e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_1dd38af7-50c1-47fc-998d-61adcd550d84" xlink:href="tln-20260331.xsd#tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:to="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_1dd38af7-50c1-47fc-998d-61adcd550d84" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_7b7149ca-fac1-4cb6-8300-1a2a961749d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_40af10a3-6624-4c8d-964f-9800a2fd5c9a" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_7b7149ca-fac1-4cb6-8300-1a2a961749d2" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.talenenergy.com/role/SegmentsScheduleofAdjustedEBITDAandReconcilingItemsDetails" xlink:type="simple" xlink:href="tln-20260331.xsd#SegmentsScheduleofAdjustedEBITDAandReconcilingItemsDetails"/>
  <link:definitionLink xlink:role="http://www.talenenergy.com/role/SegmentsScheduleofAdjustedEBITDAandReconcilingItemsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_248b2329-47c7-44f0-8071-c36042b532ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8fba6a60-2ff7-442b-ada2-26abc2565dde" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_248b2329-47c7-44f0-8071-c36042b532ca" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8fba6a60-2ff7-442b-ada2-26abc2565dde" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_7b51c28f-d8b5-4118-bdc3-303dfae534f4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8fba6a60-2ff7-442b-ada2-26abc2565dde" xlink:to="loc_srt_ConsolidationItemsAxis_7b51c28f-d8b5-4118-bdc3-303dfae534f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_7b51c28f-d8b5-4118-bdc3-303dfae534f4_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_7b51c28f-d8b5-4118-bdc3-303dfae534f4" xlink:to="loc_srt_ConsolidationItemsDomain_7b51c28f-d8b5-4118-bdc3-303dfae534f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_cd997c76-e978-402e-8dc2-eccf88ec42b0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_7b51c28f-d8b5-4118-bdc3-303dfae534f4" xlink:to="loc_srt_ConsolidationItemsDomain_cd997c76-e978-402e-8dc2-eccf88ec42b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_e82dfdb8-55eb-41d5-b057-0a5d80e8b8f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_cd997c76-e978-402e-8dc2-eccf88ec42b0" xlink:to="loc_us-gaap_OperatingSegmentsMember_e82dfdb8-55eb-41d5-b057-0a5d80e8b8f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_CorporateAndEliminationsMember_a4d2fc8b-1b40-4c00-920f-f552cebe6783" xlink:href="tln-20260331.xsd#tln_CorporateAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_cd997c76-e978-402e-8dc2-eccf88ec42b0" xlink:to="loc_tln_CorporateAndEliminationsMember_a4d2fc8b-1b40-4c00-920f-f552cebe6783" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_d0713760-39a7-43f7-a62c-3639d8077357" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_8fba6a60-2ff7-442b-ada2-26abc2565dde" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_d0713760-39a7-43f7-a62c-3639d8077357" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d0713760-39a7-43f7-a62c-3639d8077357_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d0713760-39a7-43f7-a62c-3639d8077357" xlink:to="loc_us-gaap_SegmentDomain_d0713760-39a7-43f7-a62c-3639d8077357_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_87fb74e5-bafe-4617-b5de-c519d6dccb91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_d0713760-39a7-43f7-a62c-3639d8077357" xlink:to="loc_us-gaap_SegmentDomain_87fb74e5-bafe-4617-b5de-c519d6dccb91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_PJMSegmentMember_645849dd-bb5e-4705-af53-377e82e8cc8f" xlink:href="tln-20260331.xsd#tln_PJMSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_87fb74e5-bafe-4617-b5de-c519d6dccb91" xlink:to="loc_tln_PJMSegmentMember_645849dd-bb5e-4705-af53-377e82e8cc8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllOtherSegmentsMember_8992d77b-364f-420b-85fd-23fe8e940a1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllOtherSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_87fb74e5-bafe-4617-b5de-c519d6dccb91" xlink:to="loc_us-gaap_AllOtherSegmentsMember_8992d77b-364f-420b-85fd-23fe8e940a1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AdjustedEBITDAAbstract_92295a68-3c2a-4d49-8742-08301ba4cc5b" xlink:href="tln-20260331.xsd#tln_AdjustedEBITDAAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_248b2329-47c7-44f0-8071-c36042b532ca" xlink:to="loc_tln_AdjustedEBITDAAbstract_92295a68-3c2a-4d49-8742-08301ba4cc5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_5b7dd207-74ad-4c8e-a016-dbe94c9297f9" xlink:href="tln-20260331.xsd#tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_AdjustedEBITDAAbstract_92295a68-3c2a-4d49-8742-08301ba4cc5b" xlink:to="loc_tln_AdjustedEarningsBeforeInterestTaxesDepreciationsAndAmortization_5b7dd207-74ad-4c8e-a016-dbe94c9297f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:href="tln-20260331.xsd#tln_ReconcilingItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_248b2329-47c7-44f0-8071-c36042b532ca" xlink:to="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDebtExpense_3df6aea3-432a-4357-8699-0a86679d171e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestAndDebtExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_us-gaap_InterestAndDebtExpense_3df6aea3-432a-4357-8699-0a86679d171e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_DepreciationDepletionAndAmortizationAdjusted_019c6d1a-24fe-7ac3-aa48-e40a88154a60" xlink:href="tln-20260331.xsd#tln_DepreciationDepletionAndAmortizationAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_tln_DepreciationDepletionAndAmortizationAdjusted_019c6d1a-24fe-7ac3-aa48-e40a88154a60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfNuclearFuelLease_3f6f32d9-eff8-4e8b-ae8f-120845ed3164" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfNuclearFuelLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_us-gaap_AmortizationOfNuclearFuelLease_3f6f32d9-eff8-4e8b-ae8f-120845ed3164" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_2cd2511b-5514-4bfc-8330-71846baca3d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrealizedGainLossOnCommodityContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_us-gaap_UnrealizedGainLossOnCommodityContracts_2cd2511b-5514-4bfc-8330-71846baca3d1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_667c93f9-8f24-45c1-b4de-a60afcb6f1ce" xlink:href="tln-20260331.xsd#tln_GainLossOnNuclearDecommissioningTrustFundsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_tln_GainLossOnNuclearDecommissioningTrustFundsNet_667c93f9-8f24-45c1-b4de-a60afcb6f1ce" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_a56badac-32af-4c19-b32b-2291c24f829d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeBenefitsAndShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_us-gaap_EmployeeBenefitsAndShareBasedCompensation_a56badac-32af-4c19-b32b-2291c24f829d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_AcquisitionAndDivestitureActivities_019c47c2-dc72-7ffa-af33-f3c10599b39d" xlink:href="tln-20260331.xsd#tln_AcquisitionAndDivestitureActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_tln_AcquisitionAndDivestitureActivities_019c47c2-dc72-7ffa-af33-f3c10599b39d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_tln_OperationalAndOtherRestructuringCharges_b83c76cd-9416-46d1-9500-d2fcf3b39951" xlink:href="tln-20260331.xsd#tln_OperationalAndOtherRestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_tln_OperationalAndOtherRestructuringCharges_b83c76cd-9416-46d1-9500-d2fcf3b39951" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonrecurringIncomeExpense_5874ba3b-5281-4bc5-86e0-608529a4ab5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonrecurringIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_us-gaap_OtherNonrecurringIncomeExpense_5874ba3b-5281-4bc5-86e0-608529a4ab5c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_20667f77-fd50-4927-95ca-6161fa59ca01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_tln_ReconcilingItemsAbstract_0e331659-080c-4043-882f-4fc6b92cbe13" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_20667f77-fd50-4927-95ca-6161fa59ca01" xlink:type="arc" order="10"/>
  </link:definitionLink>
</link:linkbase>
