BackgroundAdolescent depression and anxiety are major public health concerns. Aggression is frequently associated with internalizing symptoms, but the behavioral and body related mechanisms underlying this association remain insufficiently clarified. This study examined a theoretically proposed chain mediation model linking aggression with depressive and anxiety symptoms through internet addiction and somatization.MethodsA cross-sectional survey was conducted among 5,307 high school students in Chongqing, China. Participants filled in the Buss and Perry Aggression Questionnaire (BPAQ), Internet Addiction Test (IAT), Patient Health Questionnaire - 15 (PHQ - 15), Patient Health Questionnaire - 9 (PHQ - 9) and Generalized Anxiety Disorder Scale - 7 (GAD - 7). Regression based chain mediation analyses with 5,000 bootstrap samples were performed using PROCESS Model 6, with gender and age controlled as covariates.ResultsThe results showed that aggression was positively correlated with depressive symptoms (β = 0.256, p < 0.001) and anxiety symptoms (β = 0.275, p < 0.001). Chain mediation analysis showed that aggression was indirectly associated with mental health through three distinct pathways: 1. the independent mediating effect of internet addiction; 2. the independent mediating effect of somatization; 3. the sequential chain mediating effect from internet addiction to somatization. The model explained more variance in depressive symptoms (R² = 58.2%) than in anxiety symptoms (R² = 53.5%). Furthermore, the association between somatization and depressive symptoms (β = 0.457) was stronger than that between somatization and anxiety symptoms (β = 0.428).ConclusionThis study supports a statistically significant chain mediation pattern in which aggression is associated with depressive and anxiety symptoms through internet addiction and somatization. The findings suggest that somatization may represent an important body related correlate in the association between maladaptive digital behavior and emotional distress, with a slightly stronger association observed for depressive symptoms than for anxiety symptoms. These findings highlight the importance of integrated school based interventions that address digital behavior regulation, somatic symptom monitoring, and emotional distress among adolescents with higher aggressive tendencies.