Purpose: The purpose of this paper is to investigate the mediating role of prosociality, which is defined in terms of helping and benefitting others, between teacher collaboration and their turnover intentions. Prosociality was measured as prosocial impact and prosocial motivation. Design/methodology/approach: This study was conducted through a cross-sectional survey of 260 elementary and junior high school teachers in Japan. A structural equational model was employed to examine the mediating roles of prosocial impact and prosocial motivation in the relationships between teacher collaboration and their turnover intention. Findings: The results, first, supported the hypotheses: the high perception of teacher collaboration in school predicted high perceived prosocial impact; high perceived prosocial impact predicted high perceived prosocial motivation; and high perceived prosocial motivation predicted decreased turnover intention. Second, results supported partial mediating roles of prosocial impact and prosocial motivation between teacher collaboration and turnover intention. Research limitations/implications: Limitations of this study include cross-sectional data that may limit the potential for causal inferences, and self-report data. Future studies should incorporate alternative designs. Practical implications: Results indicate that teacher collaboration contributes to less teacher turnover intention via prosociality. Thus, to enhance teachers' prosocial impact, more opportunities to realise their collaboration should be considered. Originality/value: This is the first study to explore the relationships between teacher collaboration and turnover intention in educational organisations with prosociality, which resides as core goals and objectives of teachers.