Nonossifying fibromas (NOFs) are benign lesions that unusually occur in the mandible. Nonossifying fibromas are asymptomatic and spontaneous resolution at skeletal maturity. Nonossifying fibromas associated with aneurysmal bone cyst (ABC) are very rare. In this clinical report, NOF secondary to ABC in the mandibular condyle was reported; however, it presents different clinical behavior than the usual NOF. In this case, severe destruction in the mandibular condyle as a characteristic of NOF was seen. In the follow-up period, no recurrence was seen subsequent to treatment of lesion with complete resection. Treatment of NOFs with secondary ABC would require aggressive intervention than the treatment of usual NOF.