Large segmental bone defects of the phalanges reportedly have been treated with free vascularized grafts from the hand, foot, or knee, or with nonvascularized grafts from the iliac crest. A nonvascularized structural corticocancellous graft from a local site would be advantageous. The olecranon has been used as a source of both cancellous and corticocancellous graft. The authors describe a unique case of the use of nonvascularized corticocancellous olecranon bone graft for structural purposes in a mutilating thumb injury. The patient injured the left thumb with a miter saw, resulting in a large degloving wound over a severely comminuted fracture of the proximal phalanx, with segmental bone loss between a base fragment and displaced condylar fragments. Provisional pin fixation was performed at the time of initial emergent irrigation and debridement, along with repairs of the extensor pollicis longus, radial digital nerve, and dorsal digital nerve. This was followed 3 weeks later by non-vascularized corticocancellous bone grafting from the olecranon to the proximal phalanx under regional anesthesia. The thumb was mobilized at 11 weeks, and solid union was radiographically confirmed at 6 months. The patient achieved moderate active range of motion and was able to return to work as a physical therapist. The elbow healed uneventfully and without pain or fracture at the donor site. This case shows that robust structural bone graft for the phalanges may be obtained from the nearby olecranon, under regional anesthesia, without microsurgery, and with potential advantages over the iliac crest.