Reconstructive surgery to the lips requires the replacement of defective tissues with similarly functioning tissues. While non-dynamic free tissue transfers provide adequate lower lip reconstruction, improved benefits may be obtained with innervated free muscle flaps. This study reports the use of innervated serratus anterior muscle free flaps for lip reconstruction in five patients. All patients had squamous cell carcinoma of either the upper or lower lip. After resection of the tumours, the resultant defects comprised two-thirds of the lips. The innervated serratus anterior muscle free flap was transferred to the lip and an end-to-end vascular anastomosis on the facial artery was performed. The marginal mandibular branch of the facial nerve was preferred for nerve coaptation. The inner and outer surfaces of the flaps were grafted with a split-thickness skin graft. Concentric needle electromyography of the orbicularis oris and frontal muscles was performed for all patients in the preoperative, postoperative, and follow-up periods. All patients survived the surgical operation. Three patients achieved perfect oral sphincter function without drooling. Electromyography at 1 year postoperative demonstrated the successful reinnervation of the serratus anterior muscle. This study demonstrates that lip reconstruction using an innervated serratus anterior muscle free flap is a reliable method, providing a functional lower lip.