Background Understanding modifiable surgical risk factors is essential for preoperative optimization. We evaluated the association between smoking and complications following major gastrointestinal surgery. Methods Patients who underwent elective colorectal, pancreatic, gastric, or hepatic procedures were identified in the 2017 ACS NSQIP dataset. The primary outcome was 30-day death or serious morbidity (DSM). Secondary outcomes included pulmonary complications, wound complications, and readmission. Multivariable logistic regression was used to evaluate the association between smoking and these outcomes. Results A total of 46,921 patients were identified, of whom 7,671 (16.3%) were smokers. Smoking was associated with DSM (23.2% vs. 20.4%, OR 1.15 [1.08–1.23]), wound complications (13.0% vs. 10.4%, OR 1.24 [1.14–1.34]), pulmonary complications (4.9% vs 2.9%, OR 1.93 [1.70–2.20]), and unplanned readmission (12.6% vs. 11%, OR 1.14 [95% CI 1.06–1.23]). Conclusions Smoking is associated with complications following major gastrointestinal surgery. Patients who smoke should be counseled prior to surgery regarding risks.