Distal humeral fractures are relatively rare and are known to have a high nonunion rate compared to other humeral fracture sites. Treatment options for nonunion include open reduction and internal fixation (ORIF) and total elbow arthroplasty (TEA). While TEA has been increasingly reported as a treatment for distal humeral nonunion in recent years, it has limitations, including weight-bearing restrictions. This case report describes an 82-year-old female with a distal humeral nonunion that had been untreated for three years. Despite her advanced age and the prolonged time since injury, successful treatment was achieved with ORIF using dual plating technique and iliac bone grafting. Bone union was confirmed four months postoperatively, and the patient regained excellent elbow function with no pain or instability. This case suggests that ORIF can be a viable option even for elderly patients with long-standing distal humeral nonunion when appropriate surgical techniques are employed and articular surfaces are preserved.