The present study employed the social-ecological diathesis-stress model as a theoretical framework to extend previous research by examining the underlying mechanism and conditional process that contribute to the positive association between bullying victimization and internalizing problems among adolescents. A moderated mediation model involving peer autonomy support and self-esteem was tested using a sample of 1723 adolescents (50.7% girls; = 12.79,  = 1.58), who completed questionnaires assessing internalizing problems, bullying victimization, peer autonomy support, and self-esteem. The findings revealed that self-esteem partially mediated the positive association between bullying victimization and adolescents' internalizing problems. Specifically, bullying victimization was inversely related to self-esteem, which, in turn, was negatively associated with internalizing problems. Further moderation analyses demonstrated that these direct and indirect associations varied based on levels of peer autonomy support. Simple slope analyses specifically indicated that (a) peer autonomy support buffered against the negative association of bullying victimization with self-esteem and internalizing problems, and (b) peer autonomy support mitigated the negative association of self-esteem with internalizing problems. The elucidation of this mechanism and conditional process holds important implications for early interventions and prevention efforts aimed at mitigating the detrimental association of bullying victimization with adolescents' healthy emotional functions.