George Smitherman, the former deputy premier of Ontario, is now an official candidate for the mayor of Toronto.
Smitherman filed his papers Friday at city hall.
"Over the course of this campaign, I'm going to bring what I brought to public life so far: a level of energy and a capacity to be a transformative figure and to move policy files along," he said.
Smitherman served as Ontario's minister of energy and infrastructure, as well as deputy premier, until November when he handed in his resignation to Premier Dalton McGuinty.
He officially resigned as MPP for Toronto Centre at the start of the year – a riding he represented for more than a decade.
Before that he was a top aide to former Toronto mayor Barbara Hall.
During his three-term career as an MPP he was best known for his five-year stint as Ontario health minister.
Smitherman was also the first openly gay MPP in Ontario. He has said previously he doesn't believe that will be a major issue for Toronto voters.
"Will it be an issue for some people? Yes, of course, it always is. There are always people that are driven to support me because I am gay - and a certain number of people who might choose not to for the same reason."
Smitherman and his husband, Christopher Peloso, are trying to adopt a child.
In September, Toronto Mayor David Miller announced he would not be seeking re-election starting speculation about who might run to replace the mayor.On Thursday former Ontario Progressive Conservative leader John Tory said he would not be running. He had been seen as Smitherman's main rival.