Main contractor Costain has been waiting for the green light on the long delayed £260m project, originally timetabled to start in the Summer of 2022.
The Department of Transport pushed back its decision four times since being handed the planning inspectors report back in October 2021.
The original delay was blamed on the need for the Government to give its response to the Sir Peter Hendy Union Connectivity Review.
The project will receive funding reallocated from the scrapped HS2 rail project.
As well as upgrading the route to dual carriageway standard, there will be three new junctions with bridges over the A1.
