BACKGROUND: Gastric cancer is the fifth most common cancer and the fourth leading cause of death worldwide. Most cases of newly diagnosed gastric cancer involve not only locally advanced tumor growth and regional lymph node metastases but also distant metastases. We report a rare case finding of a mass in the right inguinal area which is derived from gastric cancer. CASE SUMMARY: A 68-year-old male initially diagnosed with an inguinal hernia presented with a 2 cm mass in the right inguinal area. Gastrointestinal symptoms led to the discovery of a stomach tumor. Biopsy confirmed gastrointestinal adenocarcinoma. The diagnosis was advanced gastric cancer with peritoneal dissemination, and the inguinal mass was due to direct infiltration. Due to gastrointestinal bleeding, the patient underwent palliative gastrectomy and lymph node dissection. Postoperatively, the patient received hyperthermic intraperitoneal chemotherapy and localized radiation therapy. CONCLUSION: This case indicates that a systematic evaluation should be conducted during the initial consultation to explore the potential connection between unrecognized distant masses and the primary tumor.