This study explores how knowledge leadership mitigates knowledge hiding within cross-functional project teams (CFPTs). From a psychological ownership perspective, this study hypothesizes that knowledge leadership influences knowledge hiding via the mediating effect of knowledge-based and organization-based psychological ownership. Additionally, this study proposes the moderating role of mastery climate between psychological ownership and knowledge hiding. Then, this study used a questionnaire-based survey to collect data and adopted regression analysis and bootstrapping methods to analyse the data to test the proposed hypotheses. Results indicate that (1) knowledge leadership has a negative effect on knowledge hiding; (2) both knowledge-based and organization-based psychological ownership play the mediating role between knowledge leadership and knowledge hiding; (3) the relationship between organization-based psychological ownership and knowledge hiding is moderated by mastery climate. The relationship between knowledge-based psychological ownership and knowledge hiding is also moderated by mastery climate. This study provides implications for managers to mitigate knowledge hiding within CFPTs.