This study aims to compare the concept of wasiat wajibah in the family law systems of Indonesia and Egypt, focusing on aspects such as regulation, recipients, portion size, implementation mechanisms, and its relevance to maqasid syariah. The research uses a normative-comparative legal method with a juridical-comparative approach and content analysis of primary legal materials (KHI Article 209 in Indonesia and Law No. 71 of 1946 in Egypt), secondary materials (Supreme Court of Indonesia case law, Egyptian court rulings, literature on legal reform), and tertiary materials. The results of the study show that Egypt implements wasiat wajibah in a legislative and normative manner that is clear and consistent in order to protect orphaned grandchildren (mahjub) with a share equivalent to that of parents (up to 1/3 of the estate). Meanwhile, Indonesia has adopted a more flexible judicial-pragmatic approach through Article 209 of the KHI and case law of the Supreme Court, focusing primarily on foster children/foster parents and expanding to stepchildren and relatives of different religions. The two models represent different yet complementary contemporary ijtihad in achieving justice and welfare. This study concludes that cross-learning between the two countries can strengthen the adaptability of Islamic inheritance law in the modern era.