BACKGROUND: We elucidated the influence of sarcopenic obesity on postoperative outcomes in patients with oesophago-gastric cancer. METHODS: We conducted a systematic search on MEDLINE, the Cochrane Central Register of Controlled Trials, EMBASE, the World Health Organization International Clinical Trials Platform Search Portal, and ClinicalTrials.gov to identify observational studies published from their inception to September 26, 2024. Studies involving patients who underwent radical resection for oesophago-gastric cancer and were evaluated for visceral fat mass and skeletal muscle mass through body composition were included in our analysis. The primary outcomes assessed were overall survival (OS) and postoperative complications. This protocol was registered in PROSPERO (CRD42023418403). RESULTS: Ultimately, 13 studies (involving 4912 patients) were included in our qualitative and quantitative analyses. Among these studies, three were prospective cohort studies, while the remaining 10 were retrospective cohort studies. Twelve studies specifically investigated gastric cancer, while one focused on esophageal cancer. The prevalence of sarcopenic obesity ranged from 5.7% to 28.7%. Compared to the absence of sarcopenic obesity, its presence worsens OS (hazard ratio: 1.52, 95% confidence interval: 1.08-2.15, heterogeneity (I CONCLUSIONS: Sarcopenic obesity worsens OS and increases the risk of postoperative complications in patients with oesophago-gastric cancer undergoing radical resection.