Joëlle Boutin walked away with a win in Monday's byelection in the Quebec City riding Jean-Talon, giving the Coalition Avenir Québec its 76th seat in the National Assembly.

Boutin held an early lead after polls closed, and her supporters, jam-packed into a Sainte-Foy pizza joint, cheered every time her name flashed on the screen — her lead continuing to grow throughout the evening.

Radio-Canada projected her the winner about 45 minutes after polls closed at 8 p.m.

Boutin won with about 43 per cent of the vote, beating her Liberal counterpart by more than 4,200 ballots. Voter turnout was 49 per cent.

"The citizens of Jean-Talon have chosen to give me their confidence, their trust. It's an incredible feeling," she said.

Boutin said it was a surreal experience that she will never forget. She called her win historic, as the Liberals have held the riding since it was created in 1966.

"The last Liberal bastion has fallen," said Premier François Legault, taking to the stage in front of an ecstatic crowd with Boutin at his side.

"Joëlle has run a great campaign," he said, welcoming her to the team.

The riding was left empty after former Liberal MNA and former education minister, Sébastien Proulx, quit politics in August 2019.

His would-be successor, Liberal candidate Gertrude Bourdon, was unable to maintain the party's grip on the riding.

This is the second time in two years Gertrude Bourdon has ran for office. She came in third in a Quebec City riding in the 2018 election, and second in Monday's byelection. (Sylvain Roy Roussel/CBC)

Boutin becomes the CAQ's 30th female MNA, out of a total of 76 seats.

She worked as chief of staff for Éric Caire, the minister responsible for government digital transformation. Boutin also co-founded Femmes Alpha, a leadership program for female business owners.

She came in second in 2018, tailing Proulx by 1,363 votes.

Voters had 10 names they could choose from on their ballot.

A former nurse, Bourdon was the executive director of Quebec City's hospital network, the CHU de Québec, before running for the Liberals in 2018.

She came in third place in the Jean-Lesage riding, which ended up going to Québec Solidaire's Sol Zanetti.

Québec Solidaire and the Parti Québécois were each hoping to add one seat to their caucus, with their respective candidates, Olivier Bolduc and Sylvain Barrette.

Jean-Talon had a high turnout for the 2018 election, at 75.16 per cent. In advance voting for this byelection, 20.56 per cent of voters turned up.

After the departure of former premier Philippe Couillard, who represented the riding of Roberval, Jean-Talon was the last riding the party held east of the Montreal region.