A 67-year-old woman with epigastric pain was diagnosed with resectable pancreatic head cancer and underwent pancreatoduodenectomy. Preoperative computed tomography showed that the common hepatic artery formed a common trunk with the left gastric artery running to the liver through the lesser omentum, and no other arterial supply to the liver was identified. Pancreatoduodenectomy was performed uneventfully without injury to any hepatic arteries. The postoperative clinical course was largely uneventful, and the patient was discharged on postoperative day 19. An anatomical variation of the common hepatic artery arising from a common trunk with the left gastric artery and coursing within the lesser omentum is rare. Notably, this is the first case report of pancreatoduodenectomy with this anatomical variation. Thorough understanding of hepatic arterial anatomical variations is necessary to prevent complications caused by inadvertent vascular injury and hepatic ischemia.