This study tested a moderated mediation model of transformational leadership's effects on teacher innovative practices, with teacher commitment as mediator and trust in principal as moderator. Implementing a cross-sectional survey design and using data from 611 teachers working in 56 schools in Turkey, we employed multilevel structural equation modelling with Bayesian estimation to estimate the structural links between our variables. The results provided evidence of the indirect effects of transformational leadership on teacher innovative practices through the significant mediator role of teacher commitment. We also found evidence that trust in principal acted as a significant moderator of the indirect effect of transformational leadership on teacher innovative practice through teacher commitment. This study adds nuanced evidence to the global literature by concluding that the effect of transformational leadership on teacher commitment and innovative practice is contingent upon the extent to which teachers trust their principals. We conclude with key implications for policy and practice.