Forzani, 67, was an offensive lineman with the Calgary Stampeders for seven years.
Forzani had been on life-support at the hospital in Palm Springs, Calif., after suffering either a massive stroke or heart attack.
He opened the Forzani Locker Room in 1974 and later acquired the Sport Chek chain. The Forzani Group grew to become Canada's largest sports retail business before it was sold to Canadian Tire.
Forzani stepped down from his role with the company in 2006.
Joe Forzani told CBC News his brother passed away around midnight on Thursday.