An 80-year-old woman with epigastric pain and weight loss presented to our hospital with cancer of the ascending colon and cholelithiasis. Initially hospitalized for a suspected gallstone attack, she later developed gangrenous cholecystitis. She underwent a laparoscopic cholecystectomy, which revealed abscess formation and necrosis extending into the gallbladder duct. The patient was discharged on the 10th postoperative day but was readmitted for a laparoscopic right hemicolectomy. During this surgery, extensive adhesions were encountered, which prolonged the procedure; however, it was completed with a D3 dissection. She had a successful postoperative recovery and was discharged on the 9th postoperative day. The incidence of gallstones in patients with colorectal cancer is high, and acute cholecystitis can occur. In this case, we performed a two-stage surgery and achieved a radical cure without any postoperative complications. Two-stage surgery may be an option for patients with severe symptoms and inflammation associated with acute cholecystitis.