Humeral head chondrolysis has been widely reported as a devastating complication after arthroscopic shoulder surgery; however little is known about post-arthroscopic humeral head osteonecrosis. We experienced a 66-year-old female patient with rapidly progressive osteonecrosis of the humeral head only seven months after arthroscopic Bankart and rotator cuff repair. The patient had no systemic risk factors for osteonecrosis. A satisfactory result was achieved with reverse total shoulder arthroplasty for severe humeral head destruction and an irreparable massive rotator cuff tear. Shoulder surgeons should be aware of such severe complication, perform routine radiographs, and pay close attention to the presence of constant pain or loss of motion after arthroscopic shoulder surgery.