Abstrak Seiring perkembangan zaman dan teknologi, media pembelajaran mengalami perkembangan yang pesat terutama media pembelajaran berbasis teknologi, yaitu smartphone. Namun sangat disayangkan bahwa penggunaan smartphone di Indonesia, didominasi oleh kegiatan komunikasi dan hiburan daripada kegiatan belajar. Masalah yang ditemukan ini, memotivasi sebuah penelitian pengembangan tentang aplikasi Mobile Learning yang dibuat dengan Android Studio sebagai sumber belajar dan sarana mengerjakan soal trigonometri SMA. Tujuan penelitian yaitu mengembangkan Mobile Learning yang valid, praktis dan efektif. Penelitian ini merupakan penelitian pengembangan menggunakan model ADDIE. Subjek penelitian yakni peserta didik kelas XI MIPA 2 dan 3 Semester 2 Tahun Ajar 2020/2021 SMA Kristen Satya Wacana sejumlah 10 peserta didik. Hasil validasi membuktikan bahwa Mobile Learning yang dikembangkan valid serta praktis. Hasil uji coba membuktikan bahwa aplikasi Mobile Learning dikategorikan layak dipakai dalam pembelajaran. Hasil pretest serta posttest juga menunjukkan bahwa Mobile Learning efektif meningkatkan hasil belajar, kemudian efektif menjadi sarana belajar serta mengerjakan soal matematika. The Development of Android-based PINTHIR Mobile Learning as a Learning Source and Media for Solving Trigonometry Problem in High School AbstractAlong with the times and technology, learning media has experienced rapid development, especially technology-based learning media, namely smartphones. However, it is unfortunate that the use of smartphones in Indonesia is dominated by communication and entertainment activities rather than learning activities. This problem found motivates development research on the Mobile Learning application made with Android Studio as a learning resource and a means of working on high school trigonometry problems. The research objective is to develop valid, practical, and effective Mobile Learning. This research is development research using the ADDIE model. The research subjects were 10 students of class XI MIPA 2 and 3 Semester 2 of the 2020/2021 Satya Wacana Christian High School. The validation results prove that the developed Mobile Learning is valid and practical. The trial results prove that the Mobile Learning application is categorized as suitable for use in learning. The results of the pretest and posttest also show that Mobile Learning is effective in improving learning outcomes, as well as being an effective means of learning and working on trigonometry questions.