"Over nearly two decades as an NHL coach, Paul has filled every role on a coaching staff, winning a Stanley Cup and Jack Adams trophy along the way," head coach Sheldon Keefe said. "Adding someone of Paul's expertise and character to advise and assist our staff is something that we felt was very important as we seek to make tangible steps next season."
MacLean was on the Columbus Blue Jackets bench for the 2019-20 season. He's also had stints with the Anaheim Ducks, Detroit Red Wings, and Ottawa Senators. He was the NHL's Coach of the Year with Ottawa in 2013 and won a Stanley Cup with Detroit in 2008.
His role on Toronto's bench appears to be all-encompassing.
The Leafs hired Manny Malhotra as an assistant earlier this month.