Construction is set to begin early next year to upgrade more than 29kms of the Kwinana Freeway between Roe Highway and Safety Bay Road.
A contract to deliver the project has been awarded to a consortium comprised of CPB Contractors, McConnell Dowell Constructors, Arup Australia Projects and Jacobs Group.
Detailed design will now begin on 11kms of widening from Russell Road to Mortimer Road, an extra lane southbound from Roe Highway to Berrigan Drive, and an additional lane northbound from Russell Road to Beeliar Drive.
New coordinated ramp signals will be installed on 11 northbound ramps, which will create 42 kilometres of continuous smart freeway from Safety Bay Road to the Narrows Bridge.
The $700 million upgrade, jointly funded by the Federal and State Governments, will ease congestion and improve safety across Perth's southern suburbs.
The project is expected to support up to 4180 local jobs.
Construction will begin in early 2027 when environmental approvals are complete.
Project completion is scheduled for mid-2029, with significant sections of completed widening to be opened by late 2028.
"As one of Perth's busiest roads, we know that once complete this project will have a big impact on the thousands of drivers who use the Kwinana Freeway to get to school, work and home," Premier Roger Cook said.
"Working with the Albanese Labor Government, we are delivering quality infrastructure across our State to support a high quality of life for all Western Australians."
Port Kennedy humpback whale buried at landfill facility
Secret Harbour by-election: Where to vote on August 29
Mandurah man charged over role in alleged sophisticated cybercrime syndicate
Locals urged to look out for man who removed electronic monitoring device
Four charged over brutal Warnbro home invasion allegedly linked to illicit tobacco trade
UPDATE: Sadly the whale has died overnight
City of Rockingham records steep increase in animal cruelty complaints related to untreated medical conditions
Accused dirt bike hoons charged by Mandurah Police
Heavy rainfall, thunderstorms to lash Mandurah down to Busselton