Mature Cystic Teratomas of the ovary are the most common ovarian tumors in both adolescents and reproductive-age women. This case report shows a rare case of squamous cell carcinoma arising from a mature cystic teratoma in a 59-year-old postmenopausal woman. Malignant transformation occurs in 1% of all cases of mature cystic teratomas and due to its rarity, there is no established protocol regarding optimal diagnosis and management. Preoperative diagnosis was difficult due to non-specific symptoms such as abdominal mass and abdominal pain present in this patient. The surgery was planned based on the large size of the tumor on imaging, menopausal age and a family history of breast cancer in the family. She subsequently underwent Total Abdominal Hysterectomy with Bilateral Salpingo-oophorectomy, Frozen Section, Bilateral Lymph Node Dissection, lnfracolic Omentectomy and Right Internal Iliac Artery Ligation. Final diagnosis was confirmed post operatively with the final histopathologic report. This report would show that proper risk assessment and preoperative planning would optimize management of even rare cases of malignant tumors.