Skeletal dysplasia in achondroplasia can affect all body joints — including the glenohumeral joint — and is prone to develop to degenerative osteoarthritis (OA). This may cause pain and mobility problems at young age. Surgical treatment is challenging due to the dysplastic anatomy of the shoulder joint — with a dysplastic deformed short humerus, a small, hypoplastic medialized glenoid and lateralized acromion — and the long life expectancy of these patients. The indications for reverse shoulder arthroplasty (RSA) evolved during years with rotator cuff tears and rotator cuff arthropathy in combination with or without glenohumeral OA as the main indicator, with good short to mid-term results. Long term results of RSA are rarely found in literature, especially in young patients. The use of a RSA in glenohumeral OA with an intact rotator cuff has rarely been reported. In this case report we present the ten-year clinical and radiographic results of a RSA for the treatment of degenerative OA with glenohumeral dysplasia in a young patient with achondroplasia.