This case report presents a mandible reconstruction with temporomandibular joint (TMJ) prothesis for treatment of osteomyelitis infection following a bimaxillary orthognathic and genioplasty surgeries. The patient, a 41-year-old female, presented with facial pain, difficulty in opening her mouth, and mandibular deviation four months after the initial orthognathic surgery. During the four months, the patient had experienced two more surgerys post-operative for treatment of the complications. Examination revealed mobility between osteotomy segments of the right mandibular osteotomomie between body and ramus, and Computer Tomographic scan analysis revealed osteomyelitis and non-union within the osteotomy side of the right mandible from the previous surgery. Due to the advanced state of the disease and significant bone resorption, treatment was planned in two stages, involving bone debridement and then reconstruction with a custom made extended temporomandibular joint prosthesis. The patient had no postoperative complications and achieved satisfactory functional and aesthetic outcomes. This case emphasizes the importance of careful monitoring and prompt management of postoperative complications following orthognathic surgery to prevent rare but serious complications such as osteomyelitis.