A whistle deformity is defined as a deficiency in the vertical length of the lip so that the free margins of the upper and lower lips do not meet normally, giving the appearance of whistling. This is a common secondary deformity of the vermilion in patients with cleft lip. A case involving a 61-year-old man who developed a whistle deformity as a result of two wedge resections and postoperative radiotherapy for treatment of squamous cell carcinoma of the lower lip is presented. Hyaluronic acid-based tissue filler and autologous microfat transplantation to the lower lip were used for definitive management of the patient’s whistle deformity. After one year of follow-up, the patient was pleased with the overall result and noted marked improvement of his oral competence and overall appearance of the lip. The present case demonstrates that microfat transplantation is a viable option for correcting a whistle deformity, not only after surgery, but also following adjuvant radiotherapy – both of which potentially reduce graft viability secondary to decreased vascularity of the recipient site.