The new section of the M8 is to open to traffic almost a week ahead of schedule.
The so-called missing link of Scotland's busiest motorway between Newhouse and Baillieston will open westbound on 23 April.
Economy and Infrastructure Secretary Keith Brown said the eastbound section was expected to open a week later.
It is the latest stage in the £500m M8 M73 and M74 motorway improvements project.
Transport Scotland said the work would cut journey times at peak times by around 20 minutes.
Major diversions on the M8/A8 started in February while the finishing touches were put to the new carriageway.
Mr Brown told BBC Scotland: "It will mean that for the first time main street Scotland, the road between Edinburgh and Glasgow, is motorway the whole way though and indeed 60 miles of motorway, from Edinburgh right through to Greenock.
"This is tremendous news on this substantial project."
He said he believes all the delays and congestion will have been worth it.
The minister said: "If you look at this road now there are three lanes with a hard shoulder, so the capacity has dramatically increased. We should see major improvements in terms of journey times."
Mr Brown said he has been aware of the progress as he regularly drives in the area.
He said: "My partner lives in Baillieston which has been at the centre of much of the work, so I've been aware of the changing nature of the work and diversions, and I'm from Edinburgh originally so this is a road that we use.
"It's credit to the contractors. Everybody who lives locally or uses the roads knows the level of activity there's been.
"You can see the quality of the roads built here under very difficult conditions.
"The hardest improvements are those that take place when you have to keep traffic running at the same time. That has meant congestion, but that's now coming to an end and from next Sunday we'll see phases of all the different roads affected by this opening up and improving the road experience for people right across Scotland."
Transport Scotland on the M8/A8 said the diversion was needed to remove 13,000m² of existing carriageway and 40,000m³ of earth to connect the new M8 to the existing M8, which is about 5m higher.
Around 12,000 tonnes of blacktop then had to be laid to complete the seven mile "missing link".
All work in the M8 M73 M74 improvement project is due to be completed by the end of the spring.
It has included major work at the Raith interchange of the M74 and the Shawhead junction of the M8.
Transport Scotland project manager Graeme Reid said the full benefits will be realised when all junctions and project roads open.
"Commuters between Edinburgh and Glasgow should experience a vast improvement to their journeys between Newhouse and Ballieston Interchange.
"When the M8 opens, pressure on the A8 will ease, allowing the contractor to focus on completing the upgrade of the existing A8 and linking it to the new all-purpose road."