This article discusses the recognition of the constitution, laws, and regulations, customary law, and Islamic law in the Indonesian and Malaysian legal systems through a comparative legal approach. Indonesia, which adheres to the civil law tradition of Dutch heritage, and Malaysia, which adopts common law inherited from the British, turn out to show important similarities in terms of recognition of the four sources of law. The Constitution is placed as the highest law that serves as the basic guideline for the administration of the state, while laws and regulations function as the main instrument to translate the mandate of the Constitution. Customary law in both countries is still recognized as long as it does not conflict with national regulations, reflects local cultural identity, and plays a role in resolving community disputes. Meanwhile, Islamic law has received formal space through religious courts in Indonesia and sharia courts in Malaysia, especially in family, inheritance, and morality matters. This study uses a normative legal method with a comparative approach, supported by primary and secondary legal materials. The results of the study show that despite the different systems, Indonesia and Malaysia have succeeded in combining colonial heritage with local and religious identities, so that the legal system is plural, dynamic, but still integrated. These findings enrich comparative legal studies in Southeast Asia and make an academic contribution to understanding the dynamics of legal pluralism in cognate regions.