Several major roads on the South Coast and Southern NSW will be transformed under a $37.5 million investment by the State Government to upgrade more than 470 kilometres of state-managed roads.

Transport for NSW is undertaking a 10-month spray sealing program at more than 20 state road corridors from Broken Hill to Byron Bay and as far south as Eden.

In Southern NSW, $8.38 million will be spent on nearly 100km of roads, including the Princes Highway, Moss Vale Road, Illawarra Highway, Snowy Mountains Highway, Kosciuszko Road, Hume Highway, Federal Highway, Appin Road and Monaro Highway with works starting this month to be completed by April.

The advanced technology applies a protective layer of hot bitumen and aggregate that waterproofs roads against heavy rain damage while providing superior grip in all weather conditions – extending road life by up to 10 years.

This investment builds on the already announced $155 million pothole and road repair blitz on state roads across regional NSW.

Other areas to be upgraded are:

Western NSW ($25 million): More than 300km, including Gwydir Highway, Kamilaroi Highway, Carnarvon Highway, Newell Highway, Oxley Highway, Castlereagh Highway, Mitchell Highway, Golden Highway, Mendooran Road, plus Barrier and Silver City highways.

Northern NSW ($4.5 million): More than 70km, including New England Highway, Gwydir Highway, and Bruxner Highway.

Minister for Roads and Minister Regional Transport Jenny Aitchison said the Government was living up to its promise "to leave no community behind".

"These aren't just roads, they're lifelines connecting our regional communities to jobs, healthcare, education and each other," she said.

"Our freight operators, farmers, tourism industries, local businesses and communities depend on these corridors every single day.

"This smart investment in spray sealing prevents costly road reconstruction while delivering safer, more reliable travel for regional families.

"We're ensuring our rural and regional communities get the road infrastructure they deserve."