Craniofacial microsomia remains the second most common craniofacial deformity after cleft lip and palate. Mandibular pathology has been classically scored from type I to type III by the modified Pruzansky–Kaban classification. The authors report a case of a 5-year-old patient with Goldenhar syndrome and bilateral type III craniofacial macrosomia. The patient had absence of bilateral glenoid fossas, condyles, coronoids, and rami as well as hypoplasia of the symphysis, parasymphysis, and mandibular body. Reconstruction was performed using 2 costochondral rib autografts to reconstruct a ramus and assist in the development of a neo-glenoid fossa at the cranial base. An additional portion of costal rib graft was used to augment the deficient symphysis. The patient was placed in class III occlusion postoperatively using maxillo-mandibular fixation screws and heavy elastics. The bone grafts healed without complications with no evidence of ankylosis, nonunion, or resorption to date. For the most severe forms of craniofacial microsomia, costochondral grafting remains an effective initial technique for lengthening the hypoplastic mandible and providing a foundation for future distraction.