Background: Core decompression of the distal radius is a minimally invasive technique that has demonstrated good clinical outcomes in the treatment of Kienböck disease. However, the effectiveness of core decompression has not been compared in different age groups. The aim of this study is to compare the outcomes of core decompression in patients <45 years of age to those ≥45 years of age. Methods: This retrospective study included 36 patients with Kienböck disease who were treated with core decompression over a 20-year period. The mean follow-up was 7 years. Outcome measures included visual analogue scale pain score (VAS), active range of flexion/extension at the wrist, grip strength, and modified Mayo wrist score. The patients were divided into two age groups namely <45 years (younger group; n = 22) and ≥45 years (older group; n = 12) and the outcome measures were compared between the two age groups. Results: There were no statistically significant differences between the outcomes of the two age groups. Conclusion: The outcomes of core decompression of the distal radius for Kienböck disease in older patients (≥45 years) are favorable and similar to those seen in younger patients (<45 years). Level of Evidence: Level III (Therapeutic).