Quinn, 57, headed a consortium that purchased a majority stake in Sunderland.
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Once the takeover was finalised in July 2006 he also became manager of the Black Cats.
But after a poor start he stepped aside to make way for Keane.
The Manchester United legend then went on to win the Championship title at the end of his first season in charge, also earning promotion back to the Premier League.
Quinn has since revealed that Keane completely changed the culture both at the club and in the city of Sunderland as a whole.
Speaking to Ladbrokes Fanzone, the ex-chairman said: “Is Roy Keane a phone call away from me these days? No, definitely not, although that’s not a good or a bad thing, I must say! I don’t get to see him; I’m not at games the way I used to be.
“But looking back on my relationship with him, and particularly his time at Sunderland, I say this: He didn’t just change the culture in our dressing room, he changed the culture in the city of Sunderland.
“That’s how big a job he did, and that’s why I’ll always say the man is box office. Always was, and always will be.
“I just remember so fondly how he turned the dressing room inside out, and how he got a winning mentality back into a dressing room that had just come off a season where they had the worst points total ever, in the history of the Premier League.
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“Relegated with a shockingly low points total. There were 13 players when we got there; to turn that side into Championship winners inside nine months… it was just incredible.
“Roy brought something very special to the table, and I’m always going to be indebted to him for that, as are the group of people who owned the club at the time.
“It was an amazing performance from a young man who’d never managed before, but at the same time it wasn’t a surprise, because we’re talking about a man with a ferocious appetite for success, and for wanting to do well.”
Quinn went on to reveal that the level of which Keane was working at was so high that even the Sunderland hierarchy were left baffled.
He added: “I understand his desire to win was at a level which some of us couldn’t even understand; the ferociousness of it, and that desire to drive us.
“We’re all built a bit different, but I’ve never come across anything or anyone quite like Roy, when it came to getting a result. Every time. His attitude is just exemplary.”
Keane resigned as Sunderland manager in December 2008 and went on to manage Ipswich.
He also worked as an assistant coach at Aston Villa, Nottingham Forest and with the Republic of Ireland national team.