The purpose of this study is to determine whether increasing the use of project-based learning (PBL) by madrasa aliyah teachers in Indonesia enhances their capacity in leadership competences. This study employed a quasi-experimental approach to investigate how project-based learning (PBL) is connected with teachers' leadership competency and analyzed the data using a t-test. In general, we found that the PBL program positively affected the leadership competence of madrasa teachers in Islamic religious education learning. Also, that the PBL program positively affected students' perceptions of the level of effort a teacher exerted to provoke interest. Estimating an instrumental variable approach on the subset of schools with the most substantial increase in PBL use found that PBL was positively related to teachers' perceptions of class preparation, attempts to induce teacher interest, and the frequency with which students share ideas in class. This study introduces teaching practice as a mediating factor that affects the leadership competence of madrasa teachers, a contribution to the literature that seeks to understand the development of madrasa teachers' leadership competencies in Islamic religious education learning. This research has implications for developing the PBL model in improving the leadership competence of madrasa teachers in learning Islamic religious education.