The move could even see river valleys in Toronto added to the ring of protected land around the GTA.
The Greenbelt was created in 2005 as a measure to slow down urban sprawl.
Since that time it hasn't grown. But now there's a move to change that with the first-ever proposal to add land — specifically the Glenorchy Conservation Area in Oakville.
"Adding an area the size of Glenorchy to the Greenbelt, I hope, is the start of other additions to the Greenbelt as well," said Kevin Flynn, the Liberal MPP for Oakville.
The province is also opening the door to designating urban river valleys as part of the Greenbelt.
"It's going to mean many more people in the province are going to be directly connected to the Greenbelt," said Erin Shapero of the Ontario Greenbelt Alliance, "places like Toronto, Mississauga, Brampton. Places that have said we want to grow the Greenbelt into urban areas."
Possible additions include the river valleys of the Don and Humber in Toronto and the Credit in Mississauga.
Environmental campaigners have been pushing for Greenbelt expansion and welcome the decision.
Expanding the Greenbelt is not a done deal yet.
The government still wants to consult with the public but says there should be a decision in the new year.