Background: The current research investigated the association between teacher-student relationship (both teacher-perceived and student-perceived relationship quality) and students' prosocial behaviours, as well as the mediating roles of students' attitudes towards school and perceived academic competence in this association. Sample: Four hundred and fifty-nine Italian primary students (aged 4-9, M[subscript age] = 7.05, SD[subscript age] = 1.37) and 47 teachers (aged 26-60, M[subscript age] = 48.35, SD[subscript age] = 8.13) participated and finished all the questionnaires and scales. Methods: Multiple regression analyses and bootstrapping analyses were employed to test the direct and the mediating effects between the teacher/student-perceived relationship and students' prosocial behaviours. Results: Results indicated that (1) teacher-student relationship was positively associated with students' prosocial behaviour; and (2) students' attitudes towards school could significantly mediate the association between teacher/student-perceived relationship and students' prosocial behaviours. Conclusions: Our understanding of how teacher-student relationship helps to enhance students' prosocial behaviours, as well as the intervention programmes that aim to enhance students' prosocial behaviours, may benefit from these findings.