Steatotic liver disease after pancreatoduodenectomy occurs due to various factors, such as exocrine pancreatic insufficiency, impaired intestinal absorption, and malnutrition. The mechanism of steatogenesis differs to that of conventional steatotic liver disease associated with obesity and insulin resistance. We experienced a rare case of rapidly progressive steatotic liver disease accompanied by portal vein stenosis in the early postoperative period after subtotal stomach-preserving pancreaticoduodenectomy for distal cholangiocarcinoma. Although there was a complication due to postoperative drain infection, the patient was discharged from hospital with no nutritional problems. Two months postoperatively, the patient presented to the emergency room with dyspnea. CT showed a markedly steatotic liver, ascites, and portal vein stenosis. A portal vein stent was inserted transhepatically and the steatotic liver disease gradually improved. During the postoperative course, there were no problems indicated by nutritional markers; although the patient had diarrhea associated with postoperative pancreatic exocrine insufficiency, the symptoms were mild and improved after administration of oral pancrelipase. Before the intervention, the patient had intestinal edema, exacerbation of diarrhea, and a low serum zinc concentration, suggesting that impaired absorption caused by intestinal blood stasis and gut barrier dysfunction contributed to the development of steatotic liver disease.