Gliomatosis peritonei is an extremely rare condition usually associated with either immature teratoma or, less commonly, mature teratoma. We present a case of a young female with long-standing progressive abdominal distension, who was diagnosed with mature ovarian teratoma with gliomatosis peritonei and gross ascites. The final diagnosis in this case was determined through the correlation of imaging, operative, and histopathological findings. The presence of enhancing peritoneal nodules usually leads to a suspicion of peritoneal carcinomatosis or abdominal tuberculosis, especially in endemic regions; however, gliomatosis peritonei should always be considered in the differential diagnosis, particularly when associated with teratomas. Radiological findings combined with histopathological reports are valuable in reaching the final diagnosis in these cases.