Background: The increasing utilization of Kredit Pemilikan Rumah (KPR) schemes in Indonesia has generated complex legal relationships among consumers, banks, and property developers, particularly within Buy Back Guarantee (BBG) arrangements. Legal disputes emerge when debtors experience default while land certificates remain registered under developers’ names, and developers settle debtor obligations through BBG mechanisms. Through subrogation, developers may obtain creditor positions while maintaining formal ownership, creating uncertainty regarding unilateral cancellation of Perjanjian Pengikatan Jual Beli (PPJB), property repossession, and enforcement of rights over financed assets. Objective: This study examines the legality of unilateral PPJB cancellation and property repossession conducted by developers based on subrogation deeds, as well as the legal consequences arising from the dual position of developers as formal property owners and substituted creditors. Methods: This research applies a normative juridical approach using statutory, conceptual, and case approaches. Legal materials consist of primary legal sources, secondary legal literature, and judicial decisions related to mortgage financing, subrogation, PPJB, and BBG mechanisms. Results: The findings indicate that subrogation does not automatically grant developers the authority to unilaterally cancel PPJBs or repossess properties without fulfilling contractual obligations and applicable legal procedures. The developer’s role as a substituted creditor must be separated from its capacity as the registered owner of the property. Conclusion: Legal certainty in KPR practices requires compliance with good faith principles, judicial oversight, and clear contractual arrangements regarding default and subrogation consequences. This study contributes to strengthening legal understanding of the relationship between property rights, contractual obligations, and creditor protection in Indonesian housing financing.