Background <p>Mental health is an important aspect of adolescents’ development and well-being. Mental health problems, such as depression, anxiety, non-suicidal self-injury, suicide ideation, and suicide attempt, are recognized to be interconnected and to occur often. Research has found that aggression is connected to a variety of mental health problems. However, there’s limited knowledge about the patterns of how depression, anxiety, non-suicidal self-injury, suicide ideation, and suicide attempt co-occur, and only few studies describe their association with aggression and sex differences.</p> Methods <p>A cross-sectional study that involved 18,555 Chinese adolescents was performed to explore the mental health latent classes and the relationship with aggression.</p> Results <p>The results showed four latent classes of mental health problems: low-symptom class (70.8%), self-harm class (9.1%), emotional symptom class (13.4%), and high-symptom class (6.7%). A significant co-occurrence between depression, anxiety, non-suicidal self-injury, suicide ideation, and suicide attempt was found in the high-symptom class. Notably, higher levels of adolescent aggression were associated with comorbid moderate to high mental health problems. Similar four latent classes and associations were found across sexes.</p> Conclusions <p>The present study emphasized the heterogeneity of mental health problems and revealed their co-occurrence patterns. Aggression levels are associated with the latent classes in adolescents, with the most pronounced association observed in the high-symptom class. Preventing aggression could contribute to reducing the severity and co-occurring patterns of mental health problems among adolescents.</p>