We present a case of a woman in her 50s with a rapidly expanding giant serous cystadenofibroma of the ovary. The 40-kg mass displaced her bowel and splinted her diaphragm, causing mass effect and acute respiratory compromise worsening over a 6-week period. Due to complex features on imaging and raised tumour blood markers, suspicion of malignancy was raised. Therefore, surgical cytoreduction was necessary. In this case, complex multiple comorbidities, including morbid obesity with a BMI of 62.7, posed significant surgical and anaesthetic challenges. This case highlights the complex diagnostic, intraoperative and perioperative challenges in managing giant ovarian cysts in multimorbid obese patients.