The Scottish Roads Partnership (SRP), a consortium with Ferrovial Agroman and Lagan, was named as the preferred bidder for the ambitious scheme.
Work will start on the project later this year, with completion due in the spring of 2017.
The project will complete the motorway network between Glasgow and Edinburgh by upgrading the A8 Baillieston to Newhouse. It also includes work to improve the Raith Interchange, as well as widening key sections of the M8, M73 and M74.
When completed, the new section of road will lessen peak-time journeys by up to 18 minutes for vehicles using the busy sections of the M8 each day.
Transport Minister Keith Brown said: "The Scottish Government is continuing to invest in our transport infrastructure and the improvements made by this project will have long-lasting benefits for people across the central belt and beyond.
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"This project will boost the nation's economy by improving connections for business across Scotland and will directly support the hard-pressed construction industry. The M74 Completion generated 900 construction jobs and we expect this project to be on a similar scale. There will also be opportunities for on the job training for apprentices and local employment.
"These improvements will also greatly improve road safety and accessibility by playing an essential role in reducing frustration and accidents and providing easier access to and from a number of communities and locations, such as Strathclyde Park."
This is the first roads infrastructure scheme to be procured as part of the £2.5bn Scottish Government's Non-Profit Distributing Model (NPD).
Work on the site is expected to begin later this year, with the project currently on track to be completed by Spring 2017. As the scheme progresses, Transport Scotland will hold a series of public exhibitions later this year to keep local communities and road users informed.
Earlier this year, Transport Scotland awarded a £3.1m groundworks contract to Forkers Ltd. This was the first of a series of advance works planned for the scheme which is now complete, allowing advance utility diversions to be undertaken ahead of the main construction works.
(JP/MH)
