The $2.1 billion M12 Motorway will open to motorists in the early hours of 14 March following four years of construction.

The new 16-kilometre motorway will connect Elizabeth Drive in the east to The Northern Road in the west, providing an intersection-free route to the Western Sydney International Airport precinct.

The motorway is expected to play a key role in supporting the development of the Western Sydney Aerotropolis, a major innovation and employment hub planned around the new airport.

Designed to integrate with the wider road network, the project will improve connectivity for motorists and freight operators travelling across Western Sydney.

The final component of the project, the M7-M12 Interchange at Cecil Hills, is scheduled to open later this year and will provide a motorway-to-motorway connection between the M12 and the Westlink M7.

The motorway between Elizabeth Drive and The Northern Road will open ahead of the first cargo and passenger flights scheduled to begin later this year at the new airport.

The project has been jointly funded by the Federal Government and the Government, with the Federal Government contributing $1.63 billion and the NSW Government providing $408 million.

Once operational, the M12 is expected to remove around 25,000 vehicles a day from local roads, helping reduce congestion on surrounding suburban streets and improving travel time reliability across the region.

Authorities have also tested signage, lane markings and driver guidance systems across key connections to help motorists become familiar with the route before opening.

Project highlights include: