Penelitian ini bertujuan untuk mengembangkan media pembelajaran mobile learning berbasis android pada materi notasi sigma di kelas XI Madrasah Aliyah Negeri (MAN) 3 Medan. Kualitas produk yang dikembangkan dinilai berdasarkan aspek kevalidan, kepraktisan, dan keefektifan. Prosedur pengembangan media pembelajaran mengacu pada model pengembangan 4-D, yaitu Define (Pendefinisian), Design (Perancangan), Develop (Pengembangan), dan Disseminate (Penyebaran). Subjek penelitian ini adalah siswa kelas XI MAN 3 Medan berjumlah 15 orang siswa. Kualitas kevalidan media pembelajaran memenuhi kriteria valid berdasarkan skor rata-rata lembar penilaian media yaitu 4,63 dari skor maksimal 5,00 dengan kriteria sangat baik. Kualitas kepraktisan media pembelajaran berdasarkan persentase rata-rata angket respon siswa yaitu 43,36% artinya hampir dari setengah siswa mengatakan bahwa media yang dikembangkan praktis digunakan. Kepraktisan media didukung oleh persentase keterlaksanaan pembelajaran menunjukkan 93,33% pembelajaran terlaksana dengan sangat baik. Keefektifan media memenuhi kriteria efektif dengan tingkat sedang dengan adanya peningkatan skor rata-rata pre test yakni 30 ke nilai post test yakni 52. Hal ini diperkuat dengan uji normalitas gain yang menunjukkan skor 0,31 yang menunjukkan adanya keefektifan media pada tingkat sedang. Kata Kunci : Media Pembelajaran; Mobile Learning; Android.   ABSTRACT   This study aims to develop android-based mobile learning learning media on sigma notation material in class XI Madrasah Aliyah Negeri (MAN) 3 Medan. The quality of the developed products was assessed based on aspects of validity, practicality, and effectiveness. The instructional media development procedure refered to the 4-D development model, namely Define, Design, Develop, and Disseminate. The subjects of this research were 15 students of class XI MAN 3 Medan. The quality of the validity of the learning media met the valid criteria based on the average score of the media assessment sheet, which is 4.63 out of a maximum score of 5.00 with very good criteria. The practicality quality of learning media was based on the average percentage of student response questionnaires, which was 43.36%, meaning that almost half of students said that the media developed was practical to use. The practicality of the media was supported by the percentage of implementation of learning which shows 93.33% of learning was carried out very well. The effectiveness of the media met the criteria of being effective at a moderate level with an increase in the average pre-test score of 30 to the post-test value of 52. This was reinforced by the gain normality test which shows a score of 0.31 which indicates the effectiveness of the media at a moderate level. Keywords: Learning Media, Mobile Learning, Android