Mesenteric ischemia (MI) is a condition characterized by compromised intestinal perfusion, leading to varied patterns of bowel hypoxia that requires prompt diagnosis and surgical intervention. Here, we report a case in which indocyanine green (ICG) was utilized to evaluate intestinal blood flow in a patient with acute-on-chronic MI. A 65-year-old underweight female presented with abdominal pain out of proportion to exam and was found to have diffuse aortic atherosclerotic disease with chronic occlusion of both superior and inferior mesenteric arteries with distal reconstitution. After multidisciplinary evaluation, elective treatment with vascular surgery was planned; however, on day three of her hospitalization, the patient's abdominal pain acutely worsened. She was taken to the OR for exploratory laparotomy. Under white light, the small bowel from the ligament of Treitz (LOT) to the terminal ileum and the large bowel from the cecum to the splenic flexure appeared ischemic with patchy areas of necrosis. Fluorescence angiography was then performed; injection of indocyanine green (ICG) dye and imaging with the SPY-PHI near-infrared camera system demonstrated appropriate blood flow into the bowel mesentery, with complete absence of flow into the bowel mucosal surface from the LOT to the splenic flexure, confirming irreversible bowel necrosis. Introduction of ICG intraoperatively decreased the uncertainty associated with white light assessment of bowel viability, leading to a definitive intraoperative diagnosis and clear plan of care. The use of fluorescence guidance to diagnose fulminant small and large bowel necrosis prevented the surgical team from having to perform multiple takebacks to the operating room in the setting of a nonsurvivable injury. Had the surgical team relied on the white light appearance of the bowel, they would not have been able to diagnose the true extent of bowel demise. The patient was placed on comfort care for this devastating nonsurvivable injury.