An accessory mandible is a rare congenital anomaly that requires multidisciplinary management. This case report describes a female patient with an unusual accessory mandible, a dysplastic overgrowth of bone, containing teeth that extended from the midsymphyseal region. A submucosal cleft palate and cleft of the lower lip were also present. Her treatment plan took a staged approach with initial surgical resection of the accessory bone and teeth. The second stage, still in the planning phase, will correct the secondary deformity of an anterior open bite and will restore the missing lower anterior teeth. The original deformity and subsequent growth are discussed with the relevant literature.