This systematic review and meta-analysis aimed to estimate the global prevalence of overweight and obesity in children and adolescents from 2000 to 2023 and to assess potential risk factors and comorbidities associated with obesity. The study included 2033 studies from 154 countries or regions, involving 45,890,555 individuals. The overall prevalence of obesity in children and adolescents was 8.5% (95% CI 8.2-8.8), with significant variations across countries, ranging from 0.4% in Vanuatu to 28.4% in Puerto Rico. Higher prevalence was observed in countries with a Human Development Index (HDI) score of 0.8 or greater and high-income regions. The prevalence increased from 7.1% (2000-2011) to 11.3% (2012-2023). Risk factors for obesity included age, sex, school type, maternal obesity, breakfast consumption, meal frequency, computer use, maternal smoking during pregnancy, birth weight, physical activity, and sleep duration. Comorbidities associated with obesity included hypertension (28.0%), dental caries (17.9%), vitamin D deficiency (11.6%), asthma (18.8%), diabetes (1.2%), flatfoot (26.1%), anxiety (25.1%), and depression (35.2%). The prevalence of overweight and excess weight was 14.8% and 22.2%, respectively. The study highlights the need for global coordinated action and national control programs to address the rising prevalence of childhood and adolescent obesity.This systematic review and meta-analysis aimed to estimate the global prevalence of overweight and obesity in children and adolescents from 2000 to 2023 and to assess potential risk factors and comorbidities associated with obesity. The study included 2033 studies from 154 countries or regions, involving 45,890,555 individuals. The overall prevalence of obesity in children and adolescents was 8.5% (95% CI 8.2-8.8), with significant variations across countries, ranging from 0.4% in Vanuatu to 28.4% in Puerto Rico. Higher prevalence was observed in countries with a Human Development Index (HDI) score of 0.8 or greater and high-income regions. The prevalence increased from 7.1% (2000-2011) to 11.3% (2012-2023). Risk factors for obesity included age, sex, school type, maternal obesity, breakfast consumption, meal frequency, computer use, maternal smoking during pregnancy, birth weight, physical activity, and sleep duration. Comorbidities associated with obesity included hypertension (28.0%), dental caries (17.9%), vitamin D deficiency (11.6%), asthma (18.8%), diabetes (1.2%), flatfoot (26.1%), anxiety (25.1%), and depression (35.2%). The prevalence of overweight and excess weight was 14.8% and 22.2%, respectively. The study highlights the need for global coordinated action and national control programs to address the rising prevalence of childhood and adolescent obesity.