Objective: Individuals whose childhood had been clouded with offline peer victimization are likely to suffer from cyberbullying in their subsequent life periods. Revealing the mechanisms underlying this linkage is a research priority with high applied values. This study responds to this research need. Method: Based on three wavedata from Chinese adolescents (N = 844, M = 13.21, SD =.39, 53% boys), this study conducted a serial mediation model involving social anxiety symptoms (SAS), problematic smartphone use (PSU), and internet gaming disorder (IGD) to understand why there often exists a positive association between early offline peer victimization and later cyberbullying victimization. In doing so, directionality in the links among SAS, PSUand IGD was clarified using a cross-lagged design, and potential gender differences in the entire model were also explored. Results: Most importantly, a developmental cascade emerged among adolescent boys (rather than girls), such that boys who carried heavier burdens of childhood offline peer victimization (recalled at Time 1) tended to display more SAS (at Time 1), which in turn were associated with higher IGD instead of PSU (at Time 2), and such internet gaming problems ultimately elevated their risk of being bullied online in adolescence (at Time 3). Notably, the link between SAS and IGD was shown to be unidirectional. Other indirect effects and gender differences were also identified. Conclusions: Our findings shed unique light on the still underexplored mechanisms underlying the phenomenon that bullying victims in early real-life settings are also often bullying victims in cyberspace. When helping bullying victims, attention should be paid to their likely disrupted social–emotional functioning and problematic media use as a result. Working on these modifiable sequelae may prevent subsequent exposure to cyberbullying. Gender differences merit consideration in such efforts.