Joly, a former lawyer and partner in a public relations firm, was the surprise runner-up to Denis Coderre in the 2013 mayor race.
"This party represents my values and I want to be part of the solution," Joly said in a statement Tuesday.
The riding is currently held by Maria Mourani, a former Bloc MP who announced she will run for the NDP in the next election.
Joly had long been considered a potential candidate under Liberal Leader Justin Trudeau, though she previously ruled out the idea in an interview with CBC.
