Construction engineering giant Leighton has won a $150 million contract to widen western Sydney's M4 motorway.

It will upgrade 7.5km of motorway, from three to four lanes in each direction, between Homebush and Parramatta, part of the first stage of the WestConnex tunnel, linking western Sydney with the airport at Botany Bay.

The widening work is due to begin in early 2015, with funding coming from the federal and NSW governments.

It’s due to be finished by 2017, and will connect the future M4 East tunnel to Haberfield.

Leighton Holdings chief executive Marcelino Fernandez Verdes said the company was well placed to benefit as Australia upgraded its road infrastructure.

“With strong levels of investment in projects such as WestConnex, transport infrastructure will continue to be a significant market for the Leighton group,” he said in a statement on Friday.