Custom alloplastic temporomandibular joint (TMJ) reconstruction has been well established for the management of end-stage TMJ disease. However, its use in congenital TMJ deformities is limited. Here, the authors present initial outcomes of skeletally mature patients who underwent custom alloplastic TMJ reconstruction and simultaneous orthognathic surgery.A retrospective case series of patients who underwent custom alloplastic TMJ reconstruction concurrent with orthognathic surgery between 2014 and 2019 was completed. Functional, aesthetic and orthodontic outcomes as well as complications were recorded.Seven TMJs in 5 skeletally mature patients (4 female, 1 male, ages 16-30) (2 bilateral, 3 unilateral) were replaced. All but 1 patient had previous attempts at reconstructive surgery with poor results. All cases were prepared using virtual surgical planning and underwent concomitant maxillomandibular orthognathic surgery. All patients demonstrated improved post-operative occlusions. Four of 5 patients achieved >30 millimeters of post-operative MIO. Complications included ear canal perforation and facial nerve dysfunction.There were no infections or other implant-related complications. Mean follow up was 2 years and 15 days. Alloplastic TMJ reconstruction at the time of skeletal maturity for patients with congenital mandibular TMJ defects is an alternative to existing management options. Further long-term prospective outcomes studies are ongoing.