Background This study investigated the effects of reconstruction of hypopharyngeal non-circumferential defects with a submental island flap after ablation of hypopharyngeal carcinoma. Objectives The purpose of our study was to identify advantages and limitations of the submental flap for reconstruction of non-circumferential hypopharyngeal defects. Methods A total of 27 patients who had stage II-IV hypopharyngeal cancer and underwent pharyngeal reconstruction with a submental flap by the senior author in both Department of Otolaryngology Head Neck Surgery, Chinese PLA General Hospital and Department of Otolaryngology Head Neck Surgery, Beijing Friendship Hospital, Capital Medical University. Results 96.3% (26/27) cases of submental island flap survived. There were two pharyngocutaneous fistulas, one recovered spontaneously, and the other was associated with flap necrosis, underwent neck debridement and flap removal. All except for one patient had decannulation of their nasogastric tube 2 weeks postoperatively. There was no evidence of a stricture or stenosis of the laryngopharynx, nor any sign of aspiration, except for one with esophageal inlet stricture caused by radiotherapy. There were two cases of obvious paraesthesia pharynges due to beard growth at the submental flap after reconstruction. 63.0% (17/27) patients are alive and 37% (10/27) have died of disease. The 3-year survival rate is 56.3% and the 5-year survival rate is 50.0%. Conclusion The submental flap reconstruction for moderately sized non-circumferential hypopharyngeal defects is a recommended treatment option.