The motorway, which is set to start construction in 18 months' time, will link Sydney's inner west suburbs to the CBD and is expected to most affect the suburb of Concord.
Mr Pettenon is tipping a surge in property prices in the area, citing the impact on real estate values of past infrastructure.
“The WestConnex will result in quieter streets and much faster travelling times to the City, which will help drive up values in and around Concord,” said Mr Pettenon.
“In a hot market like we currently have, we could easily see prices jump in Concord on the back of this announcement by 10–15% over the next 18 months, with more tempered growth as the completion of the project draws closer.”
Mr Pettenin said the motorway will address major traffic congestion surrounding the entrance to the M4, as well as on secondary roads between Concord and Haberfield.