The shortlisted bidders for the £5m improvement project are: I & H Brown Ltd, Interserve Construction Ltd, R J McLeod (Contractors) Ltd and Roadbridge Civil Engineering & Building Contractors.
The successful bidder will construct a one kilometre section of new carriageway, to replace the existing A737 between Beith and Dalry, including new junctions.
Works will remove a double bend on the existing stretch of road and deliver safety benefits.
Minister for Transport, Humza Yousaf said: “Work is already underway to construct a bypass around Dalry and today’s announcement marks further progress in improving the A737 for communities in North Ayrshire as well as those road users travelling further distances.”
The contract is estimated to be worth approximately £5m with the final award expected in Spring 2018.