The Stampeders confirmed Forzani's passing in a statement Friday morning. The Calgary native had been on life support in a California hospital after suffering a heart attack.
After attending Utah State, John Forzani won a Grey Cup in 1971 in his first of six seasons with Calgary. He played alongside his brothers Tom and Joe.
Forzani's nephew, Johnny, was also with the club from 2010 to '12.
"John's passion for community and football were singularly essential in the revival of the Stamps' important role in the community," Stampeders chairman Ken King said in a statement. "It is one, among many, of his great legacies. I will miss him dearly."
Commissioner Mark Cohon said the CFL family was saddened by the news of Forzani's passing.
"As a league, we are immensely proud to say he was one of ours," he said in a statement. "As individuals, we are so grateful to have known him. On the field, John was a Grey Cup champion. In business, he epitomized the entrepreneurial spirit. In the community, he supported causes he believed in. And as a member of our Board of Governors, and an owner of the Calgary Stampeders, he did much to move the CFL forward.
"Gregarious and outgoing, John was a joy to be around. He not only demonstrated to us all how to reach lofty goals; he showed us how to enjoy the journey as well. Our thoughts are with his family. Like all of his other friends across the country, we will miss him, and remember him."
After retiring from football, Forzani built a chain of successful sporting goods stores exceeding 500 outlets. That chain, FGL Sports, was sold to Canadian Tire in 2011.
Forzani also established Calgary's annual Mother's Day Run and Walk in 1977, a fundraising event which continues to this day.
In 2000, the Forzani Foundation was established to assist charities including Canadian amateur athletics.
Forzani was also part of a local group that purchased the Stampeders in '05. The Calgary Flames became majority owners of the football franchise in '12 but Forzani retained a minority stake and was the team's co-chair in 2013.
Upon the arrival of the ownership group that included Forzani, the Stampeders went from a 4-14 team in 2004 to 11-7 the following season. The club has posted a winning record in nine of 10 seasons since.
Stampeders president Gordon Norrie said Forzani will forever be a key figure in the CFL club's history.
"This is a very sad day for the organization and we feel the weight of this great loss," he said. "There is absolutely no doubt the Stampeders are a better organization and team because of the efforts and dedication of John and his partners.
"On behalf of the entire organization, I extend my condolences to John's wife Linda and his children Jodi and Michael."
John Hufnagel, the Stampeders head coach and GM, was also a former teammate of Forzani's.
"I'm very saddened by John's passing," said Hufnagel. "He was a teammate, a friend and a hunting buddy.
"John was very instrumental in my return to the Stampeders organization in 2008 and I'm very proud of what we were all able to build here together."
Forzani is survived by his wife Linda and grown children Mike and Jodi.
Funeral arrangements were not immediately known.
ALSO ON HUFFPOST: