Worth £250 million, the public-private partnership (PPP) deal was awarded by the country's National Roads Authority and will see work carried out on the N17 and N18 Gort to Tuam highways.
Balfour Beatty chief executive Ian Tyler said he and his organisation are "delighted" to have been chosen for the initiative.
He said: "[This venture] will significantly improve safety and reduce journey times."
The building group will be working alongside consortium partner Bam and Mr Tyler commented it will be the first roads scheme it has delivered in Ireland.
As part of the venture, the companies will build and maintain 57km of motorway between Gort and Tuam and will include 38 bridges and a large intersection.
Last month, Balfour Beatty announced it landed an £80 million contract with Hertfordshire County Council to design and construct two secondary schools and a special needs educational facility in the region.
Posted by Charlie Parkin