AbstractIntroductionRejection sensitivity is considered a risk factor for loneliness; however, the underlying mechanisms remain unknown. Adopting the constructs of exposure, reactivity, and exposure‐reactivity from the personality framework, this study investigated three models of rejection sensitivity, bullying victimization, and loneliness to reveal why rejection sensitivity leads to loneliness among Chinese early adolescents.MethodsUsing a longitudinal design, three‐wave data were obtained (with approximately 6‐month intervals) from 2381 Chinese early adolescents (51.2% boys at Time 1, Mage = 13.38, SD = 0.59) from 7 secondary schools. Students reported on their rejection sensitivity at Time 1, bullying victimization at Times 1 and 2, and their loneliness at Times 2 and 3. A longitudinal moderated mediation model was conducted to analyze the association between variables.ResultsPath analyses demonstrated that rejection sensitivity was associated with greater loneliness for adolescents in which association was mediated by bullying victimization. High levels of rejection sensitivity exacerbate the adverse effect of bullying victimization on loneliness. Furthermore, in line with the differential exposure‐reactivity model, the effect of rejection sensitivity on loneliness mediated by bullying victimization only existed for high rejection‐sensitive adolescents.ConclusionsThe findings emphasize the dual role of rejection sensitivity in the development process of adolescents' loneliness and highlight the importance of identifying rejection‐sensitive adolescents for intervention and prevention efforts.