Mandatory wills are part of the legal instruments of Islamic inheritance in practice, influenced by the tendencies of schools of thought and the realities that occur in society. This paper examines first, how schools of jurisprudence in Muslim-majority countries influence the regulation and implementation of mandatory wills in the legal system. Second, what are the factors that influence the implementation of mandatory wills in Muslim-majority countries, and how are they implemented? This study examines Muslim-majority countries, namely Indonesia, Egypt, Morocco and Iran. Using qualitative methods, this study concludes that the interpretation of mandatory wills in Muslim countries is influenced by the schools of jurisprudence adopted, such as the Hanafi school in Egypt, the Maliki school in Morocco, the Syafi'i school in Indonesia, and the Ja'fari school in Iran. Although different in approach, all four show efforts to adapt Islamic inheritance law to social needs, both through legal reform, recognition of adopted children and non-Muslim heirs, and alternatives such as grants. Second, the factors influencing the implementation of wajibah wills in four Muslim-majority countries are influenced by four main factors: the Islamic jurisprudence schools that form the basis of inheritance law, demands for social justice that drive legal reform, the local cultural context that adapts to the dynamics of the modern family, and the national legal approach that integrates Islamic jurisprudence principles with the positive legal system. Contribution: Theoretically, the objective is to show that wajibah wills can adapt through the approach of madzhab and social dynamics. Practically, it provides a reference related to the inheritance regulations in a contextual context.[ Wasiat wajibah merupakan bagian dari instrumen hukum waris Islam dalam praktiknya turut dipengaruhi oleh kecenderungan mazhab dan realitas yang terjadi di masyarakat. Tulisan ini mengkaji pertama, bagaimana mazhab fikih di negara mayoritas muslim mempengaruhi regulasi dan implementasi wasiat wajibah dalam sistem hukum. kedua apasaja faktor-faktor yang mempengaruhi penerapan wasiat wajibah di negara mayoritas muslim dan bagaimana implementasinya. Studi ini mengkaji negara Mayoritas muslim yaitu Indonesia, Mesir, Maroko dan Iran. Dengan menggunakan metode kualitatif, studi ini menyimpulkan pertama, Penafsiran wasiat wajibah di negara-negara Muslim dipengaruhi oleh mazhab fikih yang dianut, seperti Hanafi di Mesir, Maliki di Maroko, Syafi’i di Indonesia, dan Ja’fari di Iran. Meski berbeda pendekatan, keempatnya menunjukkan upaya menyesuaikan hukum waris Islam dengan kebutuhan sosial, baik melalui reformasi hukum, pengakuan terhadap anak angkat dan ahli waris non-Muslim, maupun alternatif seperti hibah. Kedua, faktor yang mempengaruhi Penerapan wasiat wajibah di empat negara mayoritas Muslim dipengaruhi oleh empat faktor utama: mazhab fikih yang membentuk dasar hukum waris, tuntutan keadilan sosial yang mendorong reformasi hukum, konteks budaya lokal yang menyesuaikan dengan dinamika keluarga modern, serta pendekatan hukum nasional yang mengintegrasikan prinsip fikih dengan sistem hukum positif. Kontribusi: Secara teoritis tujuan menunjukkan bahwa wasiat wajibah mampu beradaptasi melalui pendekatan madzhab dan dinamika sosial. Secara praktis, memberikan acuan terkait regulasi waris secara kontekstual].