Hemimandibular hyperplasia is a facial deformity in which there is an increase in the condyle, neck of the condyle or ramus, and an occlusal cant. Different surgical treatments are proposed in the literature, from simple low or high condylectomy to more complex procedures combining osteotomies in different sites of the mandible. Surgical procedure is defined by the scintigraphic diagnosis of activity or inactivity in the center of condylar growth. The case report describes a 35-year-old female patient with hemimandibular hyperplasia on the left side with inactivity of condylar growth, successfully treated with bilateral sagittal split ramus osteotomy associated with a basilar osteotomy in form of "L" on the affected side. The surgical technique was easily executed, with an improvement in function, aesthetics, and patient satisfaction. Correction of facial asymmetry caused by excessive growth of the mandible using this basilar osteotomy in the form of "L" combined with bilateral sagittal split ramus osteotomy proved to be a relatively simple technique of easy execution with a low risk of nerve damage.