The Highways Agency has appointed Costain for the £101.7m contract to deliver improvements to the A556 in Cheshire.
The contractor won the early contractor involvement phase of the scheme in 2010, which saw it develop the detailed design and take the scheme through planning.
It will create a dual carriageway over a four-mile stretch of the A556 between the M6 junction 19 at Knutsford and the M56 junction 7 near Bowdon.
The scheme is designated a nationally significant infrastructure project by the Highways Agency.
Work will begin immediately, with the new link road expected to open in 2016/17.
Earlier this month, Costain was awarded one of five places on the £2.9bn Lot 3b of the Highways Agency’s £5bn Collaborative Delivery Framework.
Costain chief executive Andrew Wyllie said: “We are delighted to have secured the delivery phase of this vital scheme, following our successful work during the ECI phase in providing specialist design consultation and securing planning approval.
“This award is further demonstration of the importance to Costain of long-term, strategic partnerships with our customers, and our ability to deliver a range of innovative integrated services.”
The upgrade scheme aims to contribute to economic growth in the area by improving journey time reliability.