Sarcopenia is an age-related clinical syndrome caused by loss of skeletal muscle mass and function. The main causes include lack of exercise, weakened neuromuscular function, age-related hormonal changes, and increased levels of inflammatory cytokines. Gastric cancer is one of the most common digestive tract tumors in China, and ranks the second in morbidity and the third in mortality among all cancers, which seriously threatens people's health. A number of studies have shown that gastric cancer with sarcopenia can significantly affect the postoperative state and survival of patients, which is of great significance in predicting the prognosis of gastric cancer. In addition, some drugs and chemotherapy for gastric cancer can lead to chemotherapy-related sarcopenia, which has a negative influence on the treatment outcome of gastric cancer patients. In recent years, the influence of sarcopenia on gastric cancer has attracted increasing attention. Here, the authors address the pathogenesis of sarcopenia, chemotherapy-related sarcopenia, the significance of sarcopenia in predicting the prognosis of gastric cancer, and the treatment and prevention of gastric cancer complicated with concomitant sarcopenia, so as to provide new avenues for development of precise treatment protocols for gastric cancer patients.