Aim The effect of the COVID-19 pandemic on the mental health of children and adolescents is a major challenge in public health. Due to the importance of the problem the current study aimed to investigate the global prevalence of anxiety, depression, and post-traumatic stress disorder symptoms in children and adolescents during the COVID-19 pandemic.Subject and methods This study followed the PRISMA guidelines and searched online databases (PubMed, Scopus, and Web of Science) for observational studies published from January 2020 to December 2022 which determine the prevalence of anxiety, depression, and post-traumatic stress disorder symptoms in children and adolescents (age <= 18 years) during the COVID-19 pandemic.Results Overall, 23.8% (95% CI 21.5-26.1; P < 0.001, I2 = 99.8) had at least one psychological disorder. North America 40.7% (95% CI 33.2-48.3; P < 0.001, I2 = 95.3) had the highest, and East Asia 20.2% (95% CI 17.4-22.9; P < 0.001, I2 = 97.6) had the lowest prevalence of psychological disorders. The pooled prevalence of anxiety, depression, and PTSD was 26%, 23%, and 23%, respectively. The highest prevalence of anxiety was seen in Europe (43.2% (95% CI 16.9-69.6; P < 0.001, I2 = 98.6)), depression in North America (35.4 % (95% CI 29.8-41)) and PTSD in Central and South America (60.3% (95% CI 57-63.6)) respectively.Conclusion Considering the high prevalence of psychological disorders caused by the COVID-19 pandemic among children and adolescents, it is necessary to consider public health interventions to prevent its long-term effects.