Preperitoneal lipomas are rare in clinical practice. Here we report an unexpected diagnosis of a giant preperitoneal fibrolipoma detected intraoperatively during laparoscopic cholecystectomy in a 56-year-old woman. The mass was excised and a histopathological examination confirmed fibrolipoma. No recurrence was found on follow-up. In the literature, there have been many cases with unexpected diagnoses during laparoscopy. Here, we present an incidental giant preperitoneal fibrolipoma, which was overlooked by ultrasound and physical examination, but was detected during laparoscopic cholecystectomy.