BACKGROUND: Depressive and anxiety symptoms are widespread among adolescents today, creating a large social problem. However, few previous studies have addressed depression and anxiety among adolescents in Chinese cohorts. The aim of this study was to evaluate the prevalence of and risk factors for depressive and anxiety symptoms among Chinese middle school adolescent students in the post-COVID-19 era. METHODS: A total of 22,380 middle school students from Jiangsu Province were surveyed online, and their general demographic data were collected. The Patient Health Questionnaire-9 (PHQ-9) was used to assess depressive symptoms, and the seven-item Generalized Anxiety Disorder (GAD-7) scale was used to measure anxiety symptoms. RESULTS: Of these participants (aged 12-17 years), 25.6% had depressive symptoms, 26.9% had anxiety symptoms, and 20.6% had a combination of depression and anxiety symptoms. The prevalence of depressive symptoms was higher in female adolescents (27.6%) than in male adolescents (23.7%; χ = 45.479, P = 0.000), and the proportion with anxiety symptoms was higher among female adolescents (28.6%) than among male adolescents (25.4%; χ = 29.390, P = 0.000). Furthermore, binary logistic regression analysis showed that gender, region, and parental relationship were significantly associated with depressive symptoms among adolescents, while age, gender, region, and parental relationship were significantly associated with anxiety symptoms. CONCLUSIONS: Our findings demonstrated that the prevalence of reported depressive and anxiety symptoms in Chinese adolescents are high. Female gender, urban region, and poor parental relationship may be risk factors for depressive and anxiety symptoms. Furthermore, policy makers, schools, and families need to pay more attention to the psychological health of adolescents, develop response plans and take early intervention measures to reduce the prevalence of adolescent depression and anxiety.