GM officials said the expansion to a third shift is necessary to assist with the production of the Chevrolet Colorado and GMC Canyon pickups and Chevrolet Express and GMC Savana full-size vans.
It plans to add the third shift by the end of March.
GM said 97,000 people have built and priced the trucks on a company website, a sign of strong demand.
The Wentzville plant currently has 2,600 employees.
Gov. Jay Nixon, in praising the move Tuesday, cited incentives available to GM through the Missouri Manufacturing Jobs Act.
“Four years ago we came together to pass historic, bipartisan legislation aimed at revitalizing the automotive industry in Missouri,” Nixon said in a statement. “Thanks to these efforts and our outstanding skilled workforce, the Show-Me State is now at the forefront of America’s automotive comeback.