A 21-year-old female patient was referred from the department of orthodontics to our clinic for orthognathic surgery after the completion of pre-surgical orthodontic treatment. Clinically, she showed anterior open bite with Angle’s class II molar relationship. She also showed hyperplasia of the maxilla and excessive exposure of the maxillary anterior teeth at rest. Her pre-operative radiographs showed a short mandibular body length with a small SNB angle and slight maxillary canting. Her medical history was unremarkable. The patient underwent orthognathic surgery under general anesthesia. For the maxilla, 2 mm of total impaction with an additional 2 mm of posterior impaction, and canting correction was performed using LeFort I osteotomy. For the mandible, 2 mm advancement with a counterclockwise rotation was performed to close the patient’s anterior open bite and establish proper occlusion according to the maxillary movement. After these procedures, genioplasty was performed to establish the patient’s esthetic facial contour. As the required advancement amount of genioplasty was large (8 mm), a double genioplasty was performed. After all of the surgical procedures, 20 units of botulinum toxin (Meditoxin Type A, Medytox, Seoul, Korea) was injected into the anterior belly of the patient’s digastric muscle using a 1-cc syringe immediately after surgery. Relapse was evaluated via a clinical examination and a lateral cephalometric radiograph after the completion of the post-surgical orthodontic treatment. The patient’s overbite was 1.9 mm immediately after surgery and 3.2 mm 15 months post-operatively. Her overjet was 3.9 mm immediately after surgery and 3.7 mm 15 months post-operatively. The patient showed stable occlusion without any signs of relapse and was satisfied with the esthetic results.