This study aimed to investigate the effects of school- and teacher-related factors on teachers' professional learning. A quantitative cross-sectional survey design was employed using the data collected from 810 teachers in Türkiye. Path analysis was used to examine the structural relationships among variables, including instructional leadership, learning climate, teacher self-efficacy, teacher enthusiasm, teachers' attitudes towards professional development and teacher professional learning. Results validated a mediation model in which instructional leadership had direct and indirect effects on teacher professional learning. Results showed that the instructional leadership practices of school principals foster a positive learning climate that enhances teachers' self-efficacy, enthusiasm, and attitudes, ultimately supporting their professional learning. Drawing on evidence from a non-Western educational context, this study contributes to the international knowledge base by demonstrating the effects of both school- and teacher-related factors on teachers' engagement in professional learning.