Although many mallet finger injuries are effectively managed with nonoperative treatment, failure to address these bony mallet fingers can lead to complications such as soft tissue imbalances or a bony mallet malunion, ultimately resulting in a chronic mallet injury. As these chronic injuries progress, patients often report considerable functional impairment, pain, and stiffness. Various surgical techniques have been described to treat chronic mallet injuries, but many of them fail to restore DIP extension, particularly in severe cases when patients have bony malunions or hyperlaxity. This article describes a novel technique utilizing a distal phalanx osteotomy to correct a chronic mallet finger to restore full DIP extension and active range of motion of the digit. Postoperatively patients are placed in a splint with gradual motion exercises, and full activity resumption by 2.5 months. After the procedure, patients can expect improvement in their extensor lag, with outcomes similar to successful nonoperatively treated bony and tendinous mallet injuries.