This research investigated the relationships between school climates and bullying behaviors in Chinese adolescents, and tested the mediating effect of prosocial tendency according to the seesaw effect. School climates were operationalized using three constructs: subjective diversity of student development goals, teacher support, and peer trust. Bullying behaviors included traditional (i.e., physical, nonphysical, and relational) and cyber bullying behaviors. We recruited 538 adolescents from three schools in Beijing, China (286 girls, 252 boys; average age = 12.47) and asked them to fill out the surveys measuring school climates and prosocial tendency at the outset and to report school bullying behaviors three months later. The results showed that subjective diversity of student development goals and peer trust were directly associated with less cyber bullying behavior. Moreover, teacher support and peer trust were indirectly associated with less traditional bullying behaviors via prosocial tendency. Our findings extend the existing literature on the relationships between school climates and bullying behaviors by incorporating different types of bullying behaviors, concentrating on Chinese adolescents from a cultural viewpoint, and tapping into the underlying mechanism via revealing prosocial tendency as a mediator. Theoretical and empirical contributions of this study, as well as practical implications are discussed.