The CAW announced Thursday night that GM workers voted 73 per cent in favour of the new deal, reached last week.
Roughly 4,000 workers voted on the deal. The CAW has about 8,000 working at three GM plants in Ontario.
The company said it will move forward from Thursday's vote and enhance its Canadian operations to make them more competitive.
According to the union, GM promised $675 million in capital investments to be made during the next four years.
Last weekend Ford employees voted 82 per cent in favour of their four-year contract.
Chrysler employees vote this weekend.
The deals mean labour peace in the Canadian auto industry until at least 2016.
Windsor Mayor Eddie Francis said the goal now is to make sure there's new investment to keep auto manufacturing alive in Canada. Francis doesn't even want to think about losing Chrysler's Windsor Assembly Plant, where the automaker builds its popular minivans.
"Their plant and footprint is very significant to the community," Francis said.
However, Chrysler made no new investment part of the latest contract and the minivan is not guaranteed a makeover during the next four years.
Still Francis is relieved the deals are done.
"Most people are grateful they arrived at an agreement. For the last several months, there have been people on edge," Francis said.
The CAW represents about 21,000 auto workers in the country.