The Canadian Auto Workers estimated the move, which could also affect parts companies, could cost as many as 9,000 jobs in the region after all the spinoff affects are included.
The decision, which will affect workers in late 2015 or early 2016, caught union president Ken Lewenza completely by surprise and left him feeling angry and betrayed.
"We are outraged by this decision," he said. "This is about thousands of jobs in our community."
Lewenza called on the company to replace the roughly 100,000 vehicles a year worth of production in an effort to protect the jobs at the plant once the Camaro moves.
"We're going to save these jobs come hell or high water," Lewenza said.
In a statement, General Motors Canada said Wednesday that "lower capital investment and improved production efficiencies were key factors" in the move.
The current version of the Camaro has been produced since 2010 at GM's Oshawa flex plant, which employs some 2,200 people and also produces the Buick Regal and Cadillac XTS.
The CAW's most recent contract with GM, which was ratified in September, guaranteed production of the Camaro in Oshawa only until the end of the current generation.
GM said the Camaro is the only rear-wheel drive vehicle assembled at Oshawa.
Production of the next generation of Camaro will be consolidated with the production of Cadillac CTS and ATS, also rear-wheel drive vehicles, in Michigan in a bid to improve efficiency, the company said.
The CAW said the decision will cut production in Oshawa by as much as one third.
The move follows a decision by GM to invest $185 million in connection to the addition of the Cadillac XTS at the plant and the launch of a new version of the Chevrolet Impala next year.
The U.S. automaker also said it will add a third shift at the flex plant in connection with the new Impala.
The consolidated line in Oshawa will continue to produce the current generation Chevrolet Impala and Equinox until June 2014.
Lewenza, who said he spoke with the Prime Minister's Office and Ontario Premier Dalton McGuinty about the GM decision, said the government needs an industrial strategy like other countries.
"Without it, then these kind of crisis will be more regular than not regular. I can't speak for the federal government, but I do know that Premier McGuinty understands the importance of the auto industry," he said.
"Talking to both levels of government today, at least on the phone call they were equally as frustrated as I am. So all they have to do now is use the tools of government to stop this nonsense."
GM said it will continue to meet production targets agreed to with the federal and Ontario governments in 2009.
Ontario Economic Development Minister Brad Duguid said the province expected a greater level of commitment by the automaker.
"As such, we expect GM to move quickly to bring new product mandates to the facility and also stand by its commitment to add a third shift on the Oshawa Flex Line, creating 900 jobs, as announced in October," Duguid said in a statement.
"We will carefully review GM’s obligations and ensure they are accountable for those commitments."
NDP Finance critic Peggy Nash said the federal government needs to do more.
"We need the government of Canada to put some pressure on General Motors to replace the lost production in Oshawa," Nash said.
"We need to make sure we're maintaining those jobs in Oshawa, that we're using our equity stake in GM to give us a voice in the future of production in Oshawa."
The Camaro, along with the Firebird muscle car, were once produced at a GM plant in Quebec until it was shut down in 2002.
Ottawa and Ontario contributed $13.7 billion to help bail out North American automakers GM and Chrysler more than three years ago and combined own about nine per cent of GM's common shares.
In its most recent deal with GM, the CAW agreed to a plan that would see new employees take longer to reach the top of the pay scale as well as receive a hybrid pension plan.
The deal will also GM commit to creating, maintaining or extending 1,750 jobs.
Also on HuffPost