Undifferentiated carcinoma of the liver is a rare and difficult-to-detect form of primary liver cancer. We herein report the first case of undifferentiated carcinoma of the liver in a 70-year-old Japanese woman with primary biliary cholangitis. The patient was diagnosed with cStage IVA liver cancer (85 mm in diameter) and treated with hepatic arterial infusion chemotherapy, 30 Gy radiotherapy, and 11 courses of on-demand transarterial chemoembolization. Although the hepatic tumor had markedly shrunk (from 85 to 20 mm), the patient ultimately died 16 months after the diagnosis due to rapid growth of lymph node metastases.