Teachers' voice behaviour has attracted growing attention in universities due to its positive outcomes for institutional reform and improvement. This study investigated how and under what conditions university leaders' transformational leadership is beneficial to teachers' voice behaviour using data collected from 434 teachers from universities in China. As a result, we proposed a moderated mediation model of the association between transformational leadership and teachers' voice behaviour in which group voice climate was used as the mediator and team psychological safety as the moderator. The results revealed evidence of an indirect effect of transformational leadership on teachers' voice behaviour through the significant mediating role of group voice climate. Moreover, we found evidence that team psychological safety acts as a significant moderator of group voice climate and teachers' voice behaviour and strengthens the effect of the entire mediating mechanism. Specifically, the mediation effect of group voice climate was significant when team psychological safety levels were at medium or high rather than low levels. Our findings provide a deeper understanding of the benefits and effective mechanism of the impact of transformational leadership on teachers' voice behaviour in the Chinese university context and offer practical suggestions for facilitating teachers' voice behaviour in institutions.