Quinn has spent the last six years at the club, since taking over as chairman in 2006.
“I’ve had the most amazing six years,” he said.
“It gives me a huge sense of pride to see where the club is today.”
“Everything is in place for Sunderland to really make a statement, which was always my aim,” Quinn added.
“From a football perspective, securing the services of Martin O’Neill has been an absolute highlight. In Martin we have a man that understands the region, the club and the unique place it holds in the lives of its supporters and I am confident that he will harness the immense passion that exists here and take us to new heights.”
Sunderland boss Martin O’Neill added on Quinn: “Like everyone, I couldn’t be more disappointed that he has decided to step down but of course I respect and understand his decision.
“He has been the heartbeat of the football club for so long and his legacy is immeasurable. To me he is ‘Mr. Sunderland’ – and always will be.”
