Osteomas are benign osteogenic lesions that result from the proliferation of mature bone. Three variants are known: central, peripheral, and extraskeletal. The peripheral variant is the most common and it most frequently affects the paranasal sinuses, rarely occurring in the jaws. This article describes the case of a 33-year-old white male patient who was referred complaining of facial asymmetry. Clinical examination revealed an increase in volume at the base of the right side of the mandible, hard bony consistency and well delimited, painless to the touch, without signs of infection or intraoral alterations. Radiographic examination revealed an oval lobulated, radiopaque sessile lesion adhered to the mandibular base near the insertion of the masseter muscle. The patient reported practicing martial arts many years ago. Owing to the limited access, it was decided to perform the complete lesion removal through an extraoral surgical approach, by using a skin crease in the upper neck region below the lesion. The patient recovered well and the histopathological analysis confirmed the diagnosis of osteoma. The etiopathogenesis of osteoma is not completely elucidated, and 3 theories are more accepted: developmental defect, neoplastic nature, and reactive lesion owing to trauma or local infection. The clinicopathological correlation in the present case supports a traumatic origin. Traumatic peripheral osteoma should be considered in the differential diagnosis of nodular bone-forming lesions affecting the mandible.