Traumatic anterior shoulder instability is a frequent problem and often requires surgical management. In the absence of significant bone deficiency, arthroscopic capsulolabral repair is associated with low recurrence rates and good functional outcome. However, capsulolabral deficiency, particularly after multiple previous attempts at repair, may preclude traditional arthroscopic Bankart techniques. Previous reports have described the use of autograft or allograft augmentation or coracoid transfer in the treatment of this difficult problem. The purpose of this report is to describe a novel technique of arthroscopic Bankart augmentation of capsulolabral deficiency using a split subscapularis tendon flap to reinforce a damaged capsule. In the absence of bone deficiency, this technique can restore anterior shoulder restraint without excessively constraining the glenohumeral joint.