To assess the association between serum copper/zinc ratio (CZR) and overweight/obesity in children. Sociodemographic and clinical data of children aged 8–18 years old were extracted from the National Health and Nutrition Examination Survey (NHANES) database in this cross-sectional study. These associations were explored using weighted univariate and multivariate logistic regression analyses with the odds ratios (ORs) and 95% confidence intervals (CIs). High serum CZR level was related to higher odds of overweight (OR = 1.74), obesity (OR = 5.26), and central obesity (OR = 2.99). Subgroup analyses showed that high serum CZR levels were associated with high odds of overweight in children aged ≥ 12 years old (OR = 2.19) and females (OR = 2.02), while the increased odds of obesity and central obesity were found in children aged ≥ 12 years old and both male and female. Elevated serum CZR level was linked to high odds of childhood overweight, obesity, and central obesity, and this relationship was also found in children with different age and gender.