The link is a key step to improving journeys for the 142,000 vehicles that pass through the junction every day.
The 250 metre viaduct - the first completed section of the scheme - will carry M6 eastbound traffic over the M6-A14 link road onto the M1 southbound.
The road is set to open overnight on Tuesday 22 September, and will be open to traffic in time for the morning peak on Wednesday. Preparatory works will be carried out overnight on Friday 18 September.
Ivan Marriott, Highways England project manager, said:
The opening of the M6 to M1 link road is an important step forward in the scheme, enabling us to unlock other important links in the coming months, including the next stage of the A14 to M6 link road.
We thank drivers for their patience while we carry out these works and advise them to drive carefully as they get used to the new layout.
The scheme, which began in 2014, will improve junction 19 of the M1, along with sections of the M6 and the A14 within the counties of Leicestershire and Northamptonshire. Once completed, it will relieve congestion, improve journey reliability and boost safety.
Drivers are advised that traffic on the M6 southbound will be diverted at junction 1 overnight from 9pm until 6am on Friday 18 and Tuesday 22 September. The diversion will take A14 eastbound traffic towards Lutterworth via the A426 to join the M1 southbound at junction 20. M1 southbound traffic will also leave at M6 junction 1, head towards Lutterworth on the A426 before heading south on the A5 to join the M1 at junction 18.
Diversions will be clearly signposted. More information about the improvement scheme can be found on the Highways England project pages.
Members of the public should contact the Highways England customer contact centre on 0300 123 5000.
Journalists should contact the Highways England press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.