Background <p>Gastric cancer remains one of the most frequent oncological diseases, often associated with a high rate of postoperative complications. Prehabilitation has shown benefits in other surgical settings, although its role in gastric cancer patients remains under investigation.</p> Objective <p>To describe the postoperative outcomes of patients with gastric cancer who underwent a prehabilitation programme in a high-complexity referral centre in Bogotá, Colombia.</p> Methods <p>A descriptive observational retrospective cohort study was conducted at Clínica Universitaria Colombia between January 2021 and December 2023. Patients aged 18–80 years with a confirmed diagnosis of gastric cancer who underwent surgical treatment were included.</p> Results <p>A total of 140 patients with gastric cancer received prehabilitation. The mean age was 60.9 years, and 60% were male. Postoperative complications occurred in 23.6% of patients, with surgical site infection being the most frequent (17.1%). Admission to the intensive care unit was required in 7.1%, and overall mortality was 4.3%. In bivariate analysis, malnourished patients presented higher rates of total complications, surgical site infection, and ICU admission.</p> Conclusions <p>Malnutrition is consistently associated with worse postoperative outcomes. Therefore, prehabilitation plays a crucial role in improving nutritional and functional parameters that directly influence the recovery and prognosis of patients with gastric cancer.</p>