Work will start in February to upgrade the key structure on the A9 near Inverness.
The 13 span, 1,052m long cable stayed bridge crosses the Beauly Firth between North Kessock and Inverness.
There are twelve piers in total and the main span is 240m long, rising 29m above the water.
Murray Easton, Balfour Beatty, Managing Director Scotland, said: “This is an important contract for the north of Scotland and we are delighted to have been awarded it.
“We have extensive experience of working on complex bridge projects in demanding situations, for example on the M74 completion project and the Forth Road Bridge. We will draw on all that experience to carry out the contract with as little disruption as possible.”
The contract includes the installation of traffic management and refurbishment measures, waterproofing, the replacement of deck expansion joints and the retensioning of the bridge suspension cables.
Further works will include the replacement of lighting columns and safety barriers and modifications to the existing deck edge parapet.
To avoid disruption to traffic during the busy tourist season the works will be carried out in two phases: from February to June 2013 and February to June 2014.