Objective: To analyze the prevalence trends and associated factors of overweight and obesity among children and adolescents in Macao from 2005 to 2020, so as to provide evidence for developing health promotion strategies. Methods: Data were obtained from the Macao Citizen Physical Fitness Monitoring Database for the years 2005, 2010, 2015, and 2020 for participants aged 6-22 years. The χ 2 test was employed to analyze trends in detection rates, while univariate and multivariate Logistic regression analyses were conducted to identify influencing factors. Results: The overweight rate among Macaos children and adolescents increased from 10.4% in 2005 to 14.8% in 2020. The obesity rate rose from 6.8% to 12.1%, with the total detection rate increasing from 17.2% to 26.9%, and the differences were statistically significant ( χ 2 trend =46.7, 87.5, 145.9, P <0.01). Notably, the overweight/obesity rate among boys showed rapid growth ( χ 2 trend = 118.6, P <0.01), while girls exhibited a declining inflection point in 2020. Multivariate Logistic regression analysis revealed that children and adolescents with the following characteristics faced higher risks of overweight/obesity: a physical education performance score of 3 points (overweight: OR=2.34, 95%CI =1.10-4.96; obesity: OR=2.39, 95%CI =1.19-4.81), paternal obesity (overweight: OR=2.07, 95%CI =1.38-3.11; obesity: OR=1.51, 95%CI = 1.01-2.27), and maternal obesity (overweight: OR=1.69, 95%CI =1.08-2.63; obesity: OR=1.77, 95%CI =1.16- 2.71 ) ( P <0.05). Conversely, lower risks were observed in those who performed appropriate warm-up activities before exercise (obesity: OR=0.37, 95%CI =0.15-0.95), participated in two academic/non-sports extracurricular classes (obesity: OR=0.46, 95%CI =0.24-0.88), and reported moderate physical exertion during extracurricular exercise (obesity: OR=0.60, 95%CI =0.36-0.98) ( P <0.05) . Conclusions Overweight and obesity among Macao s children and adolescents remain severe, particularly among boys, while girls show early signs of improvement. It is recommended to establish a multi-sectoral collaborative prevention and control system to reduce childhood and adolescent obesity.