Truck drivers will be charged a toll to use the new $1.5 billion Perth Freight Link.
It will be Western Australia's largest road infrastructure project and will provide a direct freight route from Muchea in Perth's north to Fremantle Port.
Premier Colin Barnett says the link will remove up to 500 trucks a day from the Leach Highway, which runs through several residential suburbs.
He said heavy vehicles would possibly be banned from using other routes, but insisted the link would provide them "savings in fuel, time, in wear and tear".
Transport Minister Dean Nalder said truck drivers would save an estimated nine-and-a-half minutes a trip between the Kwinana Freeway and Fremantle, and $8.15 in vehicle operating costs.
At present, WA has no toll roads.
The Commonwealth government is providing 60 per cent of the funding for the project, while the heavy vehicle user charge will recoup part of the state government's contribution.
Its share comprises $59 million already committed to High Street upgrades and $591 million in new money.
Construction will start in early 2016.