Transport Scotland has confirmed a £500m contract to build the new M8 motorway as well as to make improvements to the M73 and M74 motorways.
The contract has been awarded to Scottish Roads Partnership (SRP), and includes the operation and maintenance of the project roads for more than 30 years.
The latest deal marks the first roads infrastructure project and the largest contract to be awarded as part of the Scottish government's £2.5bn Non-Profit Distributing (NPD) model.
SRP's construction contractor will complete the motorway network between Glasgow and Edinburgh through the construction of a new M8 between Baillieston and Newhouse.
The project includes improving the Raith Interchange in addition to widening vital sections of the M8, M73 and M74.
Transport minister Keith Brown said: "This marks a significant milestone in the timeline of what is a major transport infrastructure project for Scotland.
"Not only will these works vastly improve connectivity across Scotland's Central Belt, the project will deliver far-reaching benefits to the wider Scottish economy.
"We'll see the creation of hundreds of new jobs which will leave a lasting legacy of a highly-skilled workforce, bolstering Scotland's construction industry."
The new project will be funded by the European Investment Bank (EIB), along with a group of investors managed by Allianz Global Investors.
The new roads are expected to be open in spring 2017.