Lactic acidosis is an uncommon metabolic complication of malignancy, often associated with high tumor burden and increased mortality, and more frequently observed in hematologic malignancies than in solid tumors. This case report describes a patient with newly diagnosed signet ring cell carcinoma of the cecum, an uncommon and aggressive histological subtype of colon cancer, complicated by severe type B lactic acidosis. A 66-year-old female patient with primary signet ring cell carcinoma of the cecum and peritoneal carcinomatosis underwent a right colectomy with extended small bowel resection. Two months later, she presented to the emergency department with a partial small bowel obstruction, and laboratory studies revealed a markedly elevated lactic acid level. The patient's lactic acidosis levels remained persistently elevated despite supportive interventions, and she passed away on the fifth day of hospitalization. Cancer cells may overproduce lactate through aerobic glycolysis, known as the Warburg effect. Although rare in solid tumors, one should have a high suspicion for type B lactic acidosis in oncology patients given the associated poor prognosis and high mortality.