Genioglossus advancement （GA） is applied alone or mostly in combination with oropharyngeal operations as a part of multi-level surgery, or with definitive maxillofacial skeletal operation of maxillomandibular advancement with high success and cure rates for the treatment of obstructive sleep apnea syndrome patients by relieving airway obstruction at the hypopharyngeal level. Here we report the feasible application of this GA to the mandibular setback orthognathic surgery with diagnosed mandibular prongathism with anterior open bite in a severely obese patient in consideration of postoperative respiratory risk of the airway obstruction, followed by the successful management of perioperative and postoperative phase after bi-maxillary orthognathic surgery.