Premier Barry O'Farrell and Minister for Roads Duncan Gay announced last week the remaining two-lane sections of Camden Valley Way between Narellan Road and the M5-M7 interchange would be upgraded by the end of 2016.

Mr O'Farrell said the road was a vital piece of infrastructure for the people of south-west Sydney.

"Along with the South West Rail Link and the widening of the M5 West, the NSW government is delivering much-needed infrastructure to support this region's growing population," he said.

"The NSW government is getting on with the job of delivering infrastructure to support housing growth in south-west Sydney."

Mr Gay said the upgraded road would help connect residents and businesses across the south-west region.

"Camden Valley Way is a major arterial road linking the Hume Highway and the M7 and M5 interchange at Prestons, near Liverpool, with the historic town of Camden," he said.

"The road will be the primary route for residents of the South West Growth Centre, linking them to Camden, Narellan, Liverpool, the M7 and the M5."

The upgrade to Camden Valley Way is being delivered in four sections, two of which have already been completed.

The third section is to be completed this year and the final section to be delivered in three stages by the 2016 deadline.

The upgrade is expected to be completed around the same time as the opening of the South West Rail Link.