Abstract The Muhammadiyah Movement has become a moral and civilizational force in Indonesia; however, studies on its ethical foundations remain fragmented and have not yet been integrated in an interdisciplinary manner. This study aims to examine the ethical foundations and reformist ethos of Muhammadiyah through the perspectives of theology, philosophy, sociology, and education, as well as to formulate an integrated ethical model that connects theology, rationality, and social transformation. The study employs a qualitative approach based on a literature review. Data were collected through the identification, selection, and documentation of primary and secondary sources, then analyzed thematically. The research findings indicate that (1) the theological foundation is rooted in tawhid, al-Ma’un, and al-amr bi al-ma’ruf wa al-nahy ‘an al-munkar; (2) philosophically, Muhammadiyah harmonizes revelation and reason through the neo-akhlaqiyyah framework; (3) sociologically, this ethos is realized through anti-fatalism, community empowerment, and the formation of a modern Muslim middle class; and (4) institutionally, this ethos is embedded through 5,354 Muhammadiyah schools and 178 Muhammadiyah universities. The novelty of this research lies in its integrated theological-philosophical-sociological-educational model for understanding Islamic reform. The study affirms Muhammadiyah as a civilizational project that transforms Islamic ethics into sustainable social transformation for Indonesian society. Abstract Gerakan Muhammadiyah telah menjadi kekuatan moral dan peradaban di Indonesia, namun kajian mengenai landasan etikanya masih parsial dan belum terintegrasi secara interdisipliner. Penelitian ini bertujuan mengkaji landasan etika dan etos reformis Muhammadiyah melalui perspektif teologi, filsafat, sosiologi, dan pendidikan, serta merumuskan model etika terintegrasi yang menghubungkan teologi, rasionalitas, dan transformasi sosial. Penelitian menggunakan pendekatan kualitatif berbasis studi kepustakaan. Data dikumpulkan melalui identifikasi, seleksi, dan dokumentasi sumber primer dan sekunder, kemudian dianalisis secara tematik. Hasil penelitian menunjukkan bahwa (1) landasan teologis berakar pada tauhid, al-Ma'un, serta al-amr bi al-ma'ruf wa al-nahy 'an al-munkar; (2) secara filosofis, Muhammadiyah menyelaraskan wahyu dan akal melalui kerangka neo-akhlaqiyyah; (3) secara sosiologis, etos tersebut diwujudkan melalui anti-fatalisme, pemberdayaan masyarakat, dan pembentukan kelas menengah Muslim modern; dan (4) secara kelembagaan, etika tertanam melalui 5.354 sekolah dan 178 perguruan tinggi Muhammadiyah. Kebaruan penelitian terletak pada model teologis-filosofis-sosiologis-pendidikan terintegrasi untuk memahami reformasi Islam. Penelitian menegaskan Muhammadiyah sebagai proyek peradaban yang mentransformasikan etika Islam menjadi transformasi sosial berkelanjutan bagi kehidupan masyarakat Indonesia.