Transport and Main Roads North Coast Regional Director Scott Whitaker said the project would significantly improve the traffic flow and capacity of the Maroochydore Road and Mons Road interchanges.
"The traffic will improve particularly during peak times, as well as meet the future needs of the Sunshine Coast," Mr Whitaker said.
Work on a new four-lane bridge over the highway at Nambour is set to begin in coming weeks as part of the upgrades.
A concrete bridge will also be constructed featuring an on-road bike lane and a 3m shared pedestrian path to improve safety.
The majority of work will be undertaken at night to minimise disruption to motorists and traffic flow.