Teratomas are rare germ cell tumors derived from multiple germinal cell layers. Thyroid teratomas, specifically, are exceptionally uncommon and present unique diagnostic and therapeutic challenges. Here, we report a case of cervico-mediastinal thyroid teratoma, highlighting diagnostic difficulties and surgical management. A 37-year-old woman presented with right lateral cervical swelling, leading to radiological imaging suggesting a thymic teratoma. However, cytology indicated a colloid cyst. Surgical removal was performed, revealing a mixed-type teratoma originating from the thyroid gland. Thyroid teratomas pose diagnostic and therapeutic challenges due to their rarity and complex nature. Further research is needed to establish standardized guidelines for their management.