Osseous choristoma is a rare benign lesion composed of mature bone in an ectopic soft-tissue site, most often the posterior tongue. We report a 9-year-old girl with a 1-year history of a slowly enlarging tongue-base lesion causing dysphagia and snoring during sleep. Contrast-enhanced computed tomography showed a well-circumscribed, homogeneous bony-density lesion measuring 4.0 × 3.8 × 4.1 cm without enhancement or adjacent soft-tissue invasion. The lesion was completely excised through a dorsal tongue approach. Histopathological examination demonstrated mature osseous tissue with bony trabeculae and marrow cavities, confirming osseous choristoma. Recovery was uneventful, with no clinical recurrence at 3 months. Large tongue-base osseous choristomas may cause functional symptoms despite their benign nature. Computed tomography provides a useful diagnostic clue, while definitive diagnosis depends on histopathology. Complete surgical excision remains the treatment of choice.