Overweight or obesity is increasingly recognized as a possible risk factor for childhood asthma.We aimed to meta-analyse the association between overweight or obesity and the risk for childhood asthma and wheeze and meanwhile explore potential causes of between-study heterogeneity.Literature search, study selection, and data extraction were performed independently and in duplicate. Data were analysed by STATA software.Eighteen articles and 73 252 children were analysed. In overall analyses, there was a significant association between overweight or obesity and the risk for childhood asthma (odds ratio [OR] = 1.30; 95% confidence interval [CI], 1.23-1.39; P < 0.001) and wheeze (OR = 1.90; 95% CI, 1.38-2.63; P < 0.001), with none/marginal publication bias as revealed by the Egger test (P = 0.938/0.038), respectively. Subgroup analyses showed that children with obesity (OR = 1.40; 95% CI, 1.29-1.52) were more likely to have asthma than children with overweight (OR = 1.22; 95% CI, 1.14-1.31), and in children with overweight or obesity, girls (OR = 1.34; 95% CI, 1.16-1.56) were more likely to have asthma than boys (OR = 1.27; 95% CI, 1.15-1.40).Our findings indicate that overweight or obesity is a significant risk factor for childhood asthma and wheeze and in children with overweight or obesity, the risk is more evident in girls than in boys.