Two hours after polls closed at 8 p.m., it was clear the PQ had secured a minority government under 63-year-old Pauline Marois, who becomes Quebec's first female premier.
While 63 seats are needed to form a majority government in Quebec City's 125-seat National Assembly, the Parti Quebecois won 53, while the Liberals took 44 seats.
Although ballot counting wasn't complete at 19,680 polling stations, the new center-right CAQ party won 17 seats and the leftist and separatist Quebec Solidaire party won two.
Premier Jean Charest, who served three terms beginning in 2003, lost his seat to a PQ rival, the Canadian Broadcasting Corp. reported.
The leftist Parti Quebecois has been in power four times before beginning in 1976, then again in 1981, 1994 and 1998. Its primary goal is to secede from Canada and create a new country of Quebec.
Canadian Prime Minister Stephen Harper issued a statement thanking Charest for his service and congratulating Marois and her party for their victory. He also said the federal government trusted Quebec residents wouldn't tolerate a third referendum on independence.
"We do not believe that Quebecers wish to revisit the old constitutional battles of the past," the prime minister said.