We performed a meta-analysis to evaluate the effect of body mass index on surgical site wound infection, mortality, and postoperative hospital stay in subjects undergoing possibly curative surgery for colorectal cancer. A systematic literature search up to March 2022 was performed and 2247 subjects with possibly curative surgery for colorectal cancer at the baseline of the studies; 2889 of them were obese, and 9358 were non-obese. Odds ratio (OR) and mean difference (MD) with 95% confidence intervals (CIs) were calculated to assess the effect of body mass index on surgical site wound infection, mortality, and postoperative hospital stay in subjects undergoing possibly curative surgery for colorectal cancer using the dichotomous or contentious methods with a random or fixed-effect model. The obese subjects had a significantly higher surgical site wound infection after colorectal surgery (OR, 1.87; 95% CI, 1.62-2.15, P < .001), and higher mortality (OR, 1.58; 95% CI, 1.07-2.32, P = .02) in subjects with possibly curative surgery for colorectal cancer compared with non-obese. However, obese did not show any significant difference in postoperative hospital stay (MD, 0.81; 95% CI, -0.030 to 1.92, P = .15) compared with non-obese in subjects with possibly curative surgery for colorectal cancer. The obese subjects had a significantly higher surgical site wound infection after colorectal surgery, higher mortality, and no significant difference in postoperative hospital stay compared with non-obese in subjects with possibly curative surgery for colorectal cancer. The analysis of outcomes should be with caution because of the low number of studies in certain comparisons.