This meta-analysis synthesizes evidence about the associations of affective teacher--student relationships with bullying perpetration and peer victimization. A systematic database search resulted in 65 primary studies (k) that met the inclusion criteria. The final sample included 185,881 students from preschool to high school. Separate multilevel analyses were conducted for bullying perpetration (k = 25, N = 97,627) and peer victimization (k = 57, N = 151,653). Results showed small to medium, negative overall correlations between teacher-student relationship quality and both bullying perpetration (r = -0.17, 95% CI [-0.21, -0.14]) and peer victimization (r = -0.14, 95% CI [-0.17, -0.11]). Teacher-student relationship quality was also related to less subsequent peer victimization (b = -0.05, 95% CI [-0.08, -0.02]). Associations between teacher-student relationship quality and bullying were stronger for ethnic minority students and when the same informant reported about both variables. Associations with peer victimization were stronger for negative (e.g., conflict) than for positive (e.g., closeness) relationship indicators and when the same informant was used for both variables. Generally, findings demonstrate that higher-quality teacher-student relationships are related to less bullying perpetration and less peer victimization. Hence, promoting positive and minimizing negative teacher-student relationships may help to tackle school-based bullying and peer victimization.