Summary: Acromioclavicular joint (ACJ) cysts are a rare clinical entity that can impair patients’ cosmetic appearance as well as activities of daily living. Both nonsurgical and surgical treatments are available, but nonsurgical treatments are often associated with a high recurrence rate. Surgical excision can provide resolution of patients’ symptoms, but excision of the cyst as monotherapy is also associated with recurrence. Therefore, various surgical techniques to prevent recurrence have been described, but there is no general consensus regarding the appropriate surgical methods. We describe the case of an 81-year-old man with a recurrent ACJ cyst. The cyst had been excised twice, but it recurred shortly after the excisions. We performed surgical resection and anterolateral thigh (ALT) flap reconstruction. The deteriorated ACJ capsule was repaired with durable fascia lata and the defect after tumor excision was obliterated with an ALT flap harvested from the same donor site as fascia lata. On the 12-month follow-up, the patient had no recurrence of the ACJ cyst. Our case suggests that excision of ACJ cysts as monotherapy is likely to fail, and fascia lata patch for durable ACJ capsule reconstruction can be a viable alternative preventing cyst recurrence.