There is no consensus on the efficacy of perioperative immunonutrition in patients with upper gastrointestinal (GI) cancer surgery. We clarified the impact of perioperative immunonutrition on postoperative outcomes in patients with upper GI cancers. We searched MEDLINE (PubMed), MEDLINE (OVID), EMBASE, Cochrane Central Register of Controlled Trials, Web of Science Core Selection, and Emcare from 1981-2022 using search terms related to immunonutrition and upper GI cancer. We included randomized controlled trials. Intervention was defined as immunonutritional therapy, including arginine, n-3 omega fatty acids, or glutamine during the perioperative period. The control was defined as standard nutritional therapy. The primary outcomes were infectious complications, defined as events with a Clavien-Dindo classification grade ≥ II that occurred within 30 days after surgery. After screening, 23 studies were included in the qualitative synthesis and in the quantitative synthesis. The meta-analysis showed that immunonutrition reduced infectious complications (relative risk ratio: 0.72; 95% confidence interval: 0.57-0.92; certainty of evidence: Moderate) compared with standard nutritional therapy. In conclusion, nutritional intervention with perioperative immunonutrition in patients with upper GI cancers significantly reduced infectious complications. The effect of immunonutrition for upper GI cancers in reducing the risk of infectious complications was about 30%.