Acute aortic occlusion (AAO) is a rare and life-threatening condition, mostly secondary to acute thrombosis or embolism. It usually presents as bilateral lower limb ischemia; however, in rare cases, spinal cord infarction might coexist, mimicking cauda equina syndrome. We present a rare case of AAO by saddle embolism of a thoracic aortic mural thrombus. A 48-year-old male patient with a past medical history of ulcerative colitis and smoking was admitted with urinary and fecal incontinence, flaccid paraplegia, bilateral lower limb anesthesia, peripheral cyanosis, and pulseless lower extremities. One month earlier, he had been hospitalized due to an acute inflammatory bowel disease flare. A computed tomography (CT) angiography performed during this hospitalization revealed a pedunculated thrombus in the descending thoracic aorta, which was not present in previous imaging scans. Considering these findings, the hypothesis of acute infrarenal aortic saddle embolism of the previously identified thoracic aortic thrombus was raised and confirmed by CT angiography. Anticoagulation was immediately initiated, and the patient was submitted to emergent surgical revascularization by surgical thrombo-embolectomy with Fogarty catheters. After surgery, limb perfusion improved and the patient's neurologic deficits progressively resolved. The hypercoagulable state conferred by inflammatory bowel disease (IBD) was considered the underlying mechanism for arterial thromboembolism since other etiological investigations were negative. This case highlights the importance of recognizing atypical manifestations of AAO and reinforces the prognostic impact of early diagnosis and surgical referral since later intervention presents elevated mortality and morbidity risk. It also demonstrates the probable relationship between IBD and arterial thromboembolism risk, constituting a rare case of AAO associated with IBD.