Couillard had nearly 60 per cent of the vote and was a comfortable winner over Parti Quebecois incumbent Denis Trottier, who had held the riding since the 2007.
Couillard was running in the riding where his home is located, in the Saguenay-Lac-Saint-Jean region north of Quebec City.
He originally entered the provincial legislature by winning a byelection in the safe Montreal riding Outremont last December.
Trottier had fended off the Liberals for three straight elections and in 2012 beat his Liberal opponent by capturing 46.7 per cent of the vote.
Also on HuffPost