Shropshire Council’s portfolio holder for highways and transport, Steve Davenport, said he “guarantees” the scheme will come to fruition.
The exclusive news comes just days after Shropshire secured £54 million government funding for the Shrewsbury North West Relief Road.
Now Councillor Davenport says high level talks will take place between the government and council bosses regarding the A5.
Campaigners want the road turned into a dual carriageway between Oswestry and Montford Bridge.
It is the only section of the A5, which runs between London and Holyhead, to be single carriageway.
Councillor Davenport said: “The dualling of the A5 between north of Shrewsbury and Oswestry will happen.
“I guarantee it and it will be a massive boost for the two towns and everybody who live and work between them.
“It will bring business to the area and help those who are already based here.
“I am delighted to say plans are now moving forward at speed and we have a sit down meeting next month, which will progress things further.”
Figures released last year showed that since 1991, there have been more than 1,785 casualties on the A5 north of Shrewsbury up to the Welsh border at Chirk.
At the last count, 1,407 of these were slight, 320 were serious and 58 were fatal.
The road is seen as a vital link between the West Midlands and Wales.
Councillor Davenport said: “It is not by accident that these plans are coming to fruition.
“Shropshire Council has been working incredibly hard behind the scenes to fight for funding for these schemes.
“It feels like these projects have been on the agenda for many many years and indeed they have.
“But now they are becoming a reality. It is because we have been meeting top level government staff and ministers and lobbying them.
“I have been working hard with North Shropshire MP Owen Paterson and Shrewsbury MP Daniel Kawczynski to secure these improvements.
“It is an exciting time and it is all about making Shropshire the most attractive it can be to deliver the best jobs and opportunities."
The North West Relief Road itself will also be a huge boost to residents, motorists and workers in the Oswestry area, as it will take traffic away from the village of Baschurch and Ruyton-XI-Towns.
Councillor Nick Bardsley, member for Baschurch and Ruyton, said it will make the roads safer and be a boost to businesses.
By Andrew Morris, local democracy reporter