The long-time New Democrat MP and former city councillor made her entry into the mayoralty race official by filing her nomination papers hours after submitting her resignation as MP to the Speaker of the House of Commons.
She is expected to hold her campaign kickoff Thursday in the inner city Toronto neighbourhood of St. James Town, where she grew up.
Chow is already considered a front-runner and the only serious left-winger in the crowded mayoral race that includes one-time provincial Conservative leader and failed mayoral candidate John Tory, city councillor Karen Stintz and infamous incumbent Ford.
Her principal opponents didn't wait for the official launch of her campaign to begin painting Chow as a tax-and-spend leftie.
"She makes David Miller look like a conservative," Ford joked, referring to his predecessor.
"I'll put my proven track record of saving taxpayers' money and customer service against anyone, any day. Let the people decide," he added.
Tory's campaign issued a statement saying: "With respect to Ms. Chow, she's never met a public dollar she couldn't spend. We welcome the contrast with John who is committed to keeping taxes low and building a more livable, affordable, functional city."
However, as a member of former mayor Mel Lastman's budget committee, Chow actually earned something of a reputation for fiscal prudence.
Jamey Heath, who will be communications director for Chow's campaign, acknowledged she'll be the only "progressive" contender in the field.
But he predicted she'll appeal to people across the political spectrum, including the blue-collar folks who supported Ford's no-nonsense populism as well as those who believe it's time for a change following Ford's admitted "drunken stupors" and use of crack cocaine.
"We think there are two candidates who can appeal to sort of blue-collar, regular voters in Toronto, one of whom is Rob Ford and one of whom is Olivia Chow," Heath said.
"We don't see John Tory being able to connect with them. We think Olivia can."
Chow's campaign launch will stress her personal story, growing up in Toronto as the daughter of struggling immigrant parents, a story Heath said many Torontonians can identify with.
Ford, who was stripped of most of his powers last year after a series of personal scandals, scoffed at the notion that Chow can shake up his support base.
"My people are strong. My Ford Nation people aren't budging and we're doing great. I can't wait, it's going to get interesting."
As the widow of late NDP leader Jack Layton, Chow has always been closely associated with the New Democratic Party. But her team is emphasizing her ability to bridge partisan differences and work with people of all party stripes to get things done.
Chow's campaign will involve New Democrats like Heath and Brian Topp, who were key to Layton's success in the federal arena. But it will be headed by veteran Conservative strategist John Laschinger, who masterminded Miller's successful mayoral campaigns, while her war room will be run by Warren Kinsella, a well-known Liberal.
Her cross-partisan appeal was reflected in praise from a surprise quarter Wednesday: Employment Minister Jason Kenney, with whom Chow worked to hammer out a compromise on refugee reform legislation when the federal Conservatives headed a minority government.
"Thanks @oliviachow for yr Parliamentary service!" Kenney tweeted. "You've always shown civility & respect 4 colleagues despite policy differences. Best wishes."
In a later interview, Kenney described Chow as "a friend."
Kenney broke ranks with his more circumspect cabinet colleagues last fall when he publicly said Ford, initially considered a political ally of federal Conservatives, had "brought dishonour to public office and the office of mayor and his city" and should step aside.
Chow's departure after eight years in Parliament was greeted with "mixed emotions" from federal NDP leader Tom Mulcair, who said his party's loss is Toronto's gain.
"Olivia Chow is a fighter who will always defend the public's interest first and foremost," he said.
"I thank her wholeheartedly for her constant support and her important contributions to making Canada a fairer, more prosperous country."