Temporomandibular joint (TMJ) ankylosis or hypomobility involves fusion of the mandibular condyle to the base of the skull. It is most frequently caused by trauma, presents with restriction in mouth opening in early stages and, in children, it may result in facial growth retardation. Various methods are available for surgical correction, such as autogenous grafts, gap arthroplasty, and prosthetic reconstruction. However, such techniques present several disadvantages and may lead to relapse, decrease in the vertical height of the posterior mandible and, in the case of prosthetic reconstruction, be contraindicated for the treatment of pediatric patients. The aim of this paper is to present a case of bilateral TMJ ankylosis in a 9-year-old patient treated by the technique of vertical sliding osteotomy, a simple surgical procedure indicated for the treatment of TMJ ankylosis in children, with the results after a 3-year follow-up.