Instability of the proximal tibiofibular joint (PTFJ) is a rare clinical condition that presents unique challenges to treatment. We present the case of an active 26-year-old woman with a 4-year history of recurrent PTFJ subluxations, treated surgically at our institution using a split biceps femoris tendon graft for PTFJ reconstruction. She underwent several attempts at nonoperative management until we decided to proceed with surgical intervention. A split biceps femoris graft was used to restore stability of the PTFJ. Approximately 5 years postoperatively, she achieved full range of motion as well as functional and clinical Knee Society Scores of 94 and 90 points, respectively. To the best of our knowledge, this is the first case report of PTFJ instability treated surgically with long-term follow-up. Future studies should focus on the long-term satisfactory outcomes of soft tissue stabilization of a chronically unstable PTFJ.