Paddocks covered in long grass will soon start being transformed into the city of Bradfield, which will be built on the doorstop of the new Western Sydney International Airport.

The $1.15 billion in funding announced on Tuesday will be used primarily on basic infrastructure - including electricity, local roads and sewerage - to lure private investors to the future city.

The money will be drawn from the budget, due to be handed down on June 22.

Premier Gladys Berejiklian said the city will become one of the biggest employment hubs in the nation, during and after construction.

The city is estimated to support up to 17,600 jobs, and is envisaged to be home to advanced manufacturing, aerospace and defence industries, agri-business, pharma, freight and logistics, health and education.

"These paddocks are going to be employment hubs ... and people will be attracted here from all across Australia," the premier told reporters alongside the treasurer on Wednesday.

"A field of paddocks will become a field of dreams."

Business Council of Australia CEO Jennifer Westacott said the city of Bradfield would be a "game-changer" for the state and country.

"It will see some of the world's leading companies come and invest here, creating new industries, new high-paying, high-tech jobs," she said.

"It will also be a great place for people to live and work, (with) 36 hectares of open space."

Minister for Western Sydney Stuart Ayres said work on the city would begin by the end of the year and ramp up in 2022.

Most of the projects covered by the $1.15 billion will be completed within four years, with the rest to be completed by 2028.

The city was named after Sydney Harbour Bridge engineer John Bradfield, and will be about 60 per cent of the size of the Sydney CBD.

Australian Associated Press