Those arrested are accused of participating in fraud schemes of at least $1 million on public-works projects worth $20 million overall.
The arrests are being tied to construction projects south of Montreal, in several municipalities near the U.S. border including St-Jean-sur-Richelieu. About 77 charges have been laid against those 11, and nine companies, for suspected crimes as well as violations of federal competition laws.
The charges include breach of trust, influencing a public official, defrauding the government, producing and using counterfeit documents, accepting a bribe, extortion and conspiracy.
Those arrested Thursday were being questioned and released. They must appear in court on Sept. 7.
The arrests stem from a two-year investigation and are only the latest in a series conducted by the provincial anti-corruption squad. A public inquiry is also underway.
Around 30 people have been arrested in three major raids by the anti-corruption squad since last year, along with other isolated arrests. Eleven companies, including the nine Thursday, are also implicated.
The corruption issue is expected to loom large, along with the student-related unrest, in a provincial election expected as early as September.
One of those arrested Thursday, Gaetan Paradis, was a Liberal party volunteer who according to various reports hosted Premier Jean Charest at his house for a 2003 fundraiser.
It's the second time in two months that the province's anti-corruption squad has reportedly arrested someone who once hosted the premier at his house.
There was also a report Thursday by Radio-Canada that people tied to engineering companies, including employees and people close to them, gave $5 million to Quebec's major parties between 2001 and 2010.
A little under two-thirds of that sum went to the Liberals, who were govering for most of that time, while just under one-third went to the PQ.
The premier was asked about Thursday's arrests by reporters covering his visit to Brazil's Rio environmental summit.
"When there are problems we correct them," Charest said. "There is no quid-pro-quo with us (at the Liberal party)."