Lancashire County Council has agreed to close the Penwortham slip road from Liverpool Road onto the Guild Way flyover.
A committee decided that the road will close ahead of the construction of the new bypass, John Horrocks Way.
A spokesman for the County Council said, “Following the closure of the slip road, access to the flyover will still be possible via the roundabouts at the junctions of Leyland Road and Golden Way.
“People will still be able to head to Preston along Liverpool Road and across Penwortham Bridge. Access from Golden Way onto the flyover will be unaffected.
“John Horrocks Way and the related road layout changes in the town are part of the City Deal. This is an agreement between Lancashire Enterprise Partnership and Preston City Council, South Ribble Borough Council and Lancashire County Council, along with central government and Homes England.”
The closure of the slip road will coincide with the opening of John Horrocks Way on Monday 2 December.
The aim of the new bypass is to remove traffic through the centre of Penwortham by providing a new route from the A59 Liverpool Road at Howick to the A582 at Broad Oak Roundabout.