Background: We evaluated the clinical applications of the reconstruction of postoperative defects of the oral cavity using contralateral submental artery flaps. Methods: A retrospective study of 18 patients with postoperative intraoral cancer defects reconstructed with contralateral submental artery perforator flaps between October 2018 and October 2019 in our department was conducted. The defect area, flap size, and complications were evaluated. Results: All patients were diagnosed based on pathological examinations: 2 with adenoid cystic carcinoma and 16 with squamous cell carcinoma. The submental artery perforator flap used for simultaneous repair was 8 to 15 cm in length and 4 to 6.5 cm in width. The survival rate of flap reconstruction was 100% with no donor site complications. Conclusions: Contralateral submental artery flap reconstruction is a suitable alternative for moderate to large intraoral defects, postoperative mouth floor defects, and oral cavity composite defects of oral malignant tumors without contralateral lymph node metastases.