Background: The en bloc sliding gluteus maximus myocutaneous flap was introduced to preserve the vasculature, muscular integrity, sensory innervation, and normal gluteal contour with a midline scar in sacrococcygeal pressure ulcer reconstruction. However, its critical disadvantages include incomplete detachment of the origin of the gluteus maximus and central tension of the closed wound due to round ulcer excision. Therefore, we reviewed the surgical anatomy and applied modifications to achieve sufficient flap mobilization and to decrease complications. Methods: After fusiform or rocket-shaped ulcer excision, submuscular flap elevation was initiated by completely detaching the origin of the gluteus maximus, including the posterior iliac crest, followed by comprehensive lateral submuscular dissection in the gluteal space while preserving the neurovascular pedicles. Bony protrusions were tangentially resected from the lower sacrum and upper coccyx. After en bloc medial advancement of the bilateral flaps, defects were closed in layers, with muscle ligament fixation at the midline. Results: Twenty-nine patients underwent surgery for sacrococcygeal pressure ulcers (primary, n=22; recurrent, n=7). Transverse width of the excised ulcers was 5–12 cm (final defect, 7–15 cm). During the follow-up period (6 months to 7 years), no early postoperative complications or late aesthetic or functional discomfort occurred; however, intermittent skin sloughing occurred in four cases and one coccygeal sore recurrence occurred. The recurrent ulcer was treated using the same surgical method, with no recurrence after 2 years. Conclusion This modification can be successfully used for the reconstruction of primary and recurrent sacrococcygeal pressure ulcers.