Greening announced his retirement from professional hockey, CBC reports.
Greening was assigned to the AHL Toronto Marlies on Sunday.
Greening was designated for waivers by the Leafs on Monday.
Greening has signed a one-year deal with the Maple Leafs.
Greening was placed on waivers by the Maple Leafs on Sunday, Bob McKenzie of TSN reports.
Greening netted a goal and added an assist in 17:33 of ice time in Thursday's 4-3 win over the Flyers.
Greening had two goals in Toronto's 4-3 loss to Florida on Monday night.
Greening was called back up by the Leafs on Monday, Kevin McGran of the Toronto Star reports.
Greening was assigned to AHL Toronto on Sunday, Chris Johnston of Sportsnet reports.
Greening has joined the Maple Leafs as an emergency recall rather than the club's AHL affiliate, and is slated to draw into the lineup Thursday, Mark Masters of TSN reports.