This study tested a moderated mediation model of school leadership's relationship with teacher commitment, where teacher collaboration was treated as the mediator and teacher psychological hardiness as the moderator. Employing a cross-sectional survey design and gathering data from 553 teachers working in 61 schools in Turkiye, we performed a multilevel structural equation modelling with Bayesian estimation to estimate the structural links between the study variables. The results substantiated the direct association between school leadership and teacher commitment and indirect via teacher collaboration. Our findings also added nuance to the global literature by suggesting that teacher psychological hardiness acted as a significant moderator of school leadership' associations with teacher collaboration and teacher commitment. Key implications for policy and practice were discussed.