The head and neck regions are rather uncommon for dermoid cysts. Dermoid cysts are among the rarest types of oral cysts, accounting for a very small proportion of cases in the oral cavity. They are thought to be caused by defective development along the embryonic lines of fusion, involving both ectodermal and endodermal elements. This case study details a 16-year-old girl who complained of a smooth, globular swelling that had been present for two months over the floor of the mouth and extending to her left submandibular region. Following ultrasonography (USG) confirmation, the patient underwent a full surgical excision, and the histological report revealed a sublingual dermoid cyst.