The influence of high body mass index (BMI) on mortality and infectious outcomes of patients following open gastrointestinal surgery was unclear. This meta-analysis aimed to resolve this controversy.PubMed and EMBASE were searched by 2 researchers. High and normal BMIs were defined as ≥25 and 18.5-24.99, respectively. Odds ratios (ORs) were calculated to compare the pooled effect sizes. The primary outcome was mortality. The secondary outcome was infectious outcomes, including surgical site, pulmonary infections, and urinary tract infections.Eleven eligible articles with 51,307 patients total were included. Compared with normal BMIs, high BMIs did not increase the risk of mortality (OR, 0.78; 95% confidence interval [CI], 0.58-1.06; P = .12). The secondary outcome indicated a significantly higher risk of infectious outcomes in high-BMI patients (OR, 1.34; 95% CI; 1.13-1.58; P = .0007). Among high-BMI patients, the risks of surgical site infections (OR, 1.75; 95% CI, 1.33-2.3; P < .0001) and pulmonary infections (OR, 1.2; 95% CI, 1.02-1.40; P = .03) increased significantly; urinary tract infections (OR, 1.10; 95% CI, 0.92-1.31; P = .30) did not show statistical difference.High BMI was associated with higher risks of infectious outcomes, including surgical site infections and pulmonary infections after open gastrointestinal surgery, but no association was observed between high BMI and urinary tract infections.