The relationship between teachers and students plays a critical role in the psychosocial development of children and youth. The literature documents numerous studies over several decades that have examined links between teacher-student relationships (TSRs) and bullying perpetration and victimization among students. The present meta-analytic study provides a definitive summary of the size and the direction of the association between these variables. We synthesized the results of 18 quantitative studies (n = 20 029) that examined the association between TSR conflict and involvement in peer aggression and bullying (both perpetration and victimization) in school. Results revealed a significant positive effect of moderate size between TSR conflict and both bullying perpetration and victimization. Three moderators (grade level, informant, and scale quality) were assessed for their effects on the association between TSR conflict and peer aggression involvement. Results revealed a stronger association between bullying involvement (both bullying others and victimization) and TSR conflict (a) among elementary school students (versus secondary students), (b) when based on observer reports (versus self-reports), and (c) when researchers used well-established measures (versus new measures) of the variables. These results highlight the interconnectedness of students' relationship experiences with their teachers and their interactions in peer networks at school, and they underscore the need to consider both aspects in comprehensive climate and bullying prevention initiatives in schools.