Fibromuscular dysplasia (FMD) of the renal artery is a non-atherosclerotic, non-inflammatory vascular disease, that causes stenosis, aneurysm, dissection, and occlusion. We report a rare case of a pregnant FMD patient who presented with a sudden onset of spontaneous perirenal hematoma resulting from renal artery aneurysm rupture after her cesarean section. The 40-year-old pregnant patient, who underwent elective cesarean section at her term period of gestation, was referred to the emergency department with a sudden pain in the abdomen on her postoperative day 2. The abdominal computed tomography scan revealed perirenal hematomas with signs of FMD in both renal arteries. The bleeding was successfully controlled by a transcatheter arterial embolization, and a continuous renal replacement therapy was applied for a short period until her renal function recovered. FMD of the renal artery in a pregnant patient is a rare case and an aneurysm rupture can be a life-threatening condition requiring immediate medical attention and prompt management.