Teacher collaboration appears essential for creating a dynamic and effective educational environment that supports teachers' professional learning and growth. In various research studies, supportive school leadership has been identified as a key condition for collaborative teacher learning, which enhances teachers’ engagement and professional learning by fostering a climate of trust. Bangladesh is still struggling with the orthodoxy of leadership, which suggests a hierarchical relationship between followers and leaders, posing considerable constraints on teachers' collaboration in the school environment. Applying semi-structured interviews with thematic analysis as a data analysis instrument, this study aimed to explore the existing collaborative practices among secondary school teachers in Bangladesh and the school leaders’ approach to teachers’ collaborative practices through the lens of transformational leadership constructs. The study found a scarcity of teachers' collaborative functions in the school environment and insignificant school leadership support for teachers' collaboration. Teachers encounter considerable constraints, both individually and institutionally, due to excessive workload, inadequate infrastructure, attitudinal issues, and problems with leadership approaches. The study has implications for fostering transformational leadership, as it highlights the constructive impact on teachers' collaboration, given the noticeable absence of transformational leadership practices. Finally, the study provides recommendations for policy-level reform in designing and implementing training and professional development programs for both teachers and school leaders, with a focus on collaborative practices in similar contexts.