A 65-year-old male presented with an acute nondisplaced hook of hamate fracture while lifting a suitcase. Conservative management was employed, and he was treated with a thumb spica cast. At the most recent follow-up, he demonstrated resolution of pain and restoration of motion. CT imaging confirmed osseous union. High nonunion rates following conservative management with short arm casting without thumb immobilization for hook of hamate fractures may be in part due to inadequate immobilization. Here, use of a thumb spica cast resulted in successful osseous union following an acute hook of hamate fracture.