We report a case of functional recovery following incisional cheiloplasty for the management of lower labial edema that developed after bilateral neck dissection with preservation of the one-side internal jugular vein and postoperative chemoradiotherapy. An 81-year-old woman underwent partial maxillectomy for the treatment of maxillary gingival cancer(squamous cell carcinoma, cT1N0M0, Stage Ⅰ)in April 2013. In July 2013, she underwent bilateral neck dissection(right, modified; left, radical)for bilateral cervical lymph node recurrence with an extra-nodal spread and received postoperative chemoradiotherapy( CDDP 75 mg/m2×3 course and total radiotherapy dosage of 66 Gy). Thereafter, the patient's condition progressed without recurrence or metastasis; however, the lower labium became edematous, and severe labial dysfunction was observed. Therefore, lower labial incisional cheiloplasty was performed under local anesthesia in October 2020. An excision area of 160×14 mm was determined on the inner side of the lower labium, and excision was performed with a steel blade scalpel. Lip closure became possible one week after the operation. Seven months after the operation, the patient recovered labial function and was satisfied with the outcome.