We analyzed the relationship between preoperative nutritional indices and postoperative complications/prognoses in patients with pStage Ⅰ and Ⅱ gastric cancer aged ≥75 years who had undergone gastrectomy in our hospital. Between January 2012 and March 2021, a total of 79 cases of pStage Ⅰ and Ⅱ gastric cancer were examined in individuals aged ≥75 years who had undergone gastrectomy. We investigated the correlation between short- and long-term outcomes and the nutritional index. CONUT, GPS, and GNRI were employed as indicators of nutritional status. CONUT and GPS showed associations with postoperative complications and an extended postoperative hospital stay, whereas GNRI did not exhibit such associations. Among the patients, 7 deaths were attributed to primary diseases, whereas 16 deaths were attributed to other diseases. No correlation was found between survival rate and preoperative nutritional status. Conclusions: There were minimal cancer recurrences among older adults with gastric cancer who had undergone gastrectomy. Although preoperative nutritional status was associated with postoperative complications, it did not show an association with prognosis.