Background: Huge bladder diverticulum can mimick ovarian tumour most especially in postmenopausal women thus leading to a presentation at a gynaecological clinic. Case Reported: We report a case of a 58-year old P7+0 (6Alive) postmenopausal woman who presented at the gynaecological unit of a private facility in Akure, Ondo State with progressive abdominal swelling of 5years duration. She was earlier seen by a physician who requested for an Abdominal CT scan. She then presented with the report which did not comment on the ovaries. Considering the peak incidence of invasive epithelial ovarian cancer which usually occurs at 50-60 years of age and the small risk of false negative result in imaging study, an abdomino-pelvic ultrasound was ordered which suggested a huge bladder diverticulum. The case was co-managed with the gynaecological and urology team and she subsequently had exploratory laparotomy and open diverticulectomy with a successful outcome. Conclusion: Huge bladder diverticulum in women can present to gynaecological clinics most especially in the postmenopausal period, a high index of suspicion coupled with necessary investigations will be required to effectively manage.