We report the clinical experience of one patient with perforated duodenal diverticulitis who was successfully treated by intra-abdominal drainage and feeding jejunostomy. A 53-year-old male patient visited our hospital due to acute onset of abdominal pain and distension. Physical examination revealed tenderness over the epigastric area and right-lower quadrant of the abdomen without obvious rebound tenderness or muscle guarding. Duodenal diverticulitis with a retroperitoneal abscess was identified by abdominal computed tomography scan. Surgical intervention was performed after the failure of conservative treatment. The operative findings were compatible with perforated duodenal diverticulitis, and intra-abdominal drainage of retroperitoneal abscess with simultaneous feeding jejunostomy was undertaken. The patient was doing well at the 4-month postoperative follow-up visit. We suggest the use of a conservative operative method, as opposed to conventional diverticulectomy and duodenorrhaphy, as an alternative approach for the management of this disorder, especially when conservative treatment has failed.