Avulsion of the long digital extensor (LDE) tendon is an uncommon cause of pelvic limb lameness in the dog. Surgical exploration is recommended with reattachment of the tendon and the avulsed fragment of bone using a small screw in lag fashion. In more chronic cases, the bone fragment can be removed, and the tendon attached by suture or staple to the proximolateral tibia. Arthroscopic tenodesis of the LDE has not been previously reported in the literature. A 6-year-old male neutered Labrador Retriever was presented for evaluation of a left pelvic limb lameness that was localized to the stifle. Avulsion of the LDE tendon was diagnosed based on palpation and radiographs. Arthroscopic assessment of the joint was performed. The origin of the LDE was freed with the use of a mechanical 3.0-mm shaver and an arthroscopic punch. The freed end was then exteriorized from the lateral portal and mineralized tissue removed. The tendon end was captured using no. 2 braided suture loop using a SpeedWhip technique. A 4.75-mm SwiveLock® polyetheretherketone anchor was utilized to fasten the tendon in the proximal groove of the LDE. The dog returned to dock diving by 16 weeks postsurgery at the preinjury level of performance and remained free of lameness at 30 months postoperatively. Arthroscopic long digital tendon tenodesis is a feasible surgical option in canine patients.