ABSTRACT The free fillet flap is a well‐established reconstructive option following external hemipelvectomy. However, mitigating prolonged warm ischemia during the extensive tumor resection poses a significant challenge to flap viability. Presented herein is a case illustrating the novel use of temporary intraoperative vascular shunting to overcome this limitation. During hemipelvectomy for a 17.7 × 16.9 × 19.3 cm osteosarcoma of the proximal left femur in a 74‐year‐old man, unplanned early ischemia of the lower extremity was addressed by placing carotid shunts between the external iliac and popliteal vessels. The technique maintained continuous perfusion to the future flap for 4 h during the concurrent pelvic resection and fillet flap harvest. Definitive microvascular anastomosis was performed subsequently and the 37 × 31 cm flap remained viable postoperatively for the 3 months of follow‐up. This case report reintroduces temporary shunting as a simple, effective, and readily available technique to preserve flap perfusion in complex microsurgical reconstructions, mirroring damage‐control principles from trauma surgery.