Giant cell carcinoma (GCC) resembling the lung in the ovary is a rare and aggressive tumour with no established standard treatment options. In this case, a postmenopausal woman in her 50s with hypothyroidism underwent surgery for a left ovarian mass. Due to dense adhesions to the sigmoid colon, the procedure was abandoned, and she was referred to our centre. Imaging showed a necrotic pelvic mass involving adjacent organs, omental nodules and para-aortic lymphadenopathy. Her initial biopsy showed an undifferentiated carcinoma with giant cells, resembling GCC of the lung, which was confirmed by immunohistochemistry. Three cycles of carboplatin and paclitaxel reduced the tumour, enabling successful interval debulking surgery. The patient completed three more cycles and has been recurrence-free for 18 months. In this case, the use of neoadjuvant chemotherapy likely contributed to better disease control, facilitating a complete resection during the interval surgery.