The road scheme involves upgrades to approximately one kilometre of the existing A737 between Beith and Dalry, including new junctions.
The project follows on from the A737 Dalry bypass, for which Farrans Roadbridge JV won a £31.2m contract earlier this month.
Minister for transport Humza Yousaf said: “This highlights the significant progress we are making towards improving the A737 for the North Ayrshire communities.”
The construction of both A737 projects will mostly take place away from the existing road.
The construction value of the A737 Den Realignment contract is approximately £5m. Interested parties will be shortlisted in the summer and contract award expected in spring 2018.