Lower limb malperfusion for type A acute aortic dissection (ATAAD) is a challenging complication, particularly when it occurs suddenly during the operation. We report a 76‐year‐old female with ATAAD having thrombosed false lumen who underwent emergency hemiarch replacement with primary tear resection on the ascending aorta. After distal anastomosis, a sudden and severe drop in bilateral lower limb oxygen saturation was observed, indicating malperfusion. Subsequent angiography revealed significant stenosis of the descending aorta and iliac arteries. To avoid the additional risk of curative total arch replacement, we planned to insert stent grafts instead, restoring the flow. Follow‐up computed tomography confirmed complete resolution of malperfusion. Early intraoperative diagnosis and prompt intervention were crucial in this complex situation. This case underscores the importance of prompt management for intraoperative malperfusion.