School adjustment is an important factor in children's, and research attributes an important role to the quality of the teacher-student relationship in predicting more favourable school adjustment. The purpose of this study is to expand our knowledge of the relationship between teacher-student relationship quality and school adjustment (academic achievement, peer social preference, and problem behaviour) by examining the possible mediating role of general anxiety. We recruited a sample of 1135 Italian primary school students (51.6% girls, aged 6 [approximately 10 years, M = 7.7; SD = 0.99) and their teachers who completed an anonymous questionnaire. Results showed that a close teacher-student relationship was significantly and negatively associated with problem behaviours and positively associated with peer social status and academic achievement. Conversely, our data showed that a high-conflict teacher-student relationship was significantly and positively associated with problematic behaviours and negatively associated with peer academic achievement and social status. Our data also suggested a mediating role of general anxiety in explaining the association between a conflictual relationship with the teacher and measures of academic achievement. In this sense, a high-conflict relationship tends to be associated with high levels of general anxiety, which in turn is associated with more in problematic behaviour and worse peer social status and academic achievement.