This article discusses the internalization of Islamic legal values in efforts to overcome the crime of adultery, by highlighting the changes in the provisions of the adultery article in the old and new Criminal Codes in Indonesia. The Criminal Code only regulated adultery as sexual intercourse involving married parties, making it irrelevant to the moral values of Indonesian society that uphold religious norms and morality. The National Criminal Code of 2023 expands the scope of adultery to include any sexual relationship outside of marriage, whether the perpetrators are married or not. In Islamic law, adultery is considered a major sin, with sanctions of flogging for ghairu muhsan and stoning for muhsan, and has serious social implications. This study uses a normative legal method with a statute approach and a conceptual approach, then analyzed descriptively and analytically. The novelty of this study lies in not only classifying adultery perpetrators as married and unmarried but also examining how Islamic legal values contribute to the formation of the National Criminal Code. The research findings indicate that the National Criminal Code not only revises the adultery article but also internalizes Islamic legal values into national criminal law, reflecting the Indonesian national identity based on Pancasila. Keywords: Adultery, National Criminal Code, Islamic Law, Internalization