Objectives <p>Previous studies have primarily examined the relationships among sleep quality, self-control, and aggressive behavior. However, the direction of these associations remains unclear.</p> Methods <p>This study investigated the longitudinal relationships and underlying mechanisms among sleep quality, self-control, and aggressive behavior in early adolescents. The sample comprised 1,281 Chinese adolescents (636 girls), with a mean baseline age of 12.73&#xa0;years (<i>SD</i> = 0.68). Data were collected at four time points over two years, with six-month intervals between waves.</p> Results <p>Cross-lagged panel model (CLPM) analyses indicated that poorer sleep quality at T_n was prospectively associated with higher levels of aggressive behavior at T_n+1, and the reverse association was also observed, suggesting a bidirectional relationship between the two variables. Longitudinal mediation analyses further showed that self-control mediated the association from sleep quality to aggressive behavior, whereas it did not mediate the association from aggressive behavior to sleep quality. Multigroup analyses revealed that sleep quality was more strongly linked to subsequent aggressive behavior in boys than in girls.</p> Conclusions <p>These findings highlight the association between sleep quality and aggressive behavior among Chinese adolescents and indicate that low self-control mediates the interaction of sleep quality and aggressive behavior.</p>