Three patients with complex perineal fistula after extensive pelvic surgery and radiotherapy underwent surgical treatment combining a biological mesh for pelvic floor reconstruction and a unilateral superior gluteal artery perforator (SGAP) flap for filling of the perineal defect. All patients had both fecal and urinary diversion. Two fistulas originated from the small bowel, necessitating parenteral feeding, and one from the bladder. Symptoms included severe sacral pain and skin maceration. After laparotomy with complete debridement of the pelvic cavity, the pelvic floor was reconstructed by stitching a biological mesh at the level of the pelvic outlet. Subsequently, patients were turned to prone position, and perineal reconstruction was completed by rotating a SGAP flap into the defect between the biomesh and the perineal skin. Operating time ranged from 10 to 12.5 h, and hospital stay lasted from 9 to 23 days. The postoperative course was uneventful in all three patients. Reconstruction of large pelvic defects with a combination of biological mesh and SGAP flap is a viable alternative to a rectus abdominis musculocutaneous flap and may be preferable after extensive pelvic surgery with ostomy.