Primitive neuroectodermal tumours (PNETs) are rare malignant small round cell tumours. Notably, despite widespread reports of PNET in multiple parts of the body, it is extremely rare in the pelvis. Here, a rare case of giant PNET of the pelvis, that was treated with surgical intervention comprising hemipelvectomy and amputation, is reported. A 42-year-old female patient presented with an enlarged mass on the left hip and severe pain in the left lower extremity for the previous 6 months. Preoperative imaging examinations indicated an irregular soft tissue-like signal shadow sized 19 × 15 × 12 cm at the left ilium and sacrum. After surgical intervention involving left hemipelvectomy and amputation, the tumour was diagnosed by pathology as PNET. During the courses of postoperative radiotherapy and chemotherapy, local recurrence and distant metastasis occurred, and the patient died 9 months following surgical treatment. To the best of the authors' knowledge, the current case is the largest pelvic PNET resection reported to date. Pelvic PNET is extremely malignant and has a high mortality rate regardless of surgical treatment, however, surgical resection of the lesion may relieve the symptoms, extend life, and improve quality of life to a certain extent.