A diaphragmatic hernia is a protrusion of abdominal contents into the thoracic cavity. Although it is commonly congenital, diaphragmatic hernias can also be acquired. Blunt or penetrating trauma are among the most frequent causes, although spontaneous or iatrogenic cases have been reported. Recently, some case reports related to diaphragmatic hernia after debulking surgery for advanced ovarian cancer have been described. This is an exceedingly rare but life-threatening complication, being prompt recognition and surgical correction critical. We report a case of a delayed diaphragmatic hernia in a 19-year-old female resulting from cytoreductive surgery for advanced ovarian cancer. Rapid evolution from gastrointestinal symptoms to hypovolemic shock occurred, and intensive care admission was required. Immediate surgery was critical to improving the patient outcome. This case highlights this uncommon but life-threatening complication, the challenges of diagnosing and managing those patients, and the need for early recognition, support, and surgical correction.