The spending will fix nearly all blackspots on rural state highways where five or more fatalities have occurred over the past five years, Transport Minister Simon Bridges said.
The extra investment over six years would save lives and help address a road toll that has been rising in recent years, he said.
"Ninety high-risk sites are going to receive these improvements, really across the length and breadth of New Zealand."
The Government has repeatedly stressed that poor driver decisions are behind most fatalities.
Today's announcement is an acknowledgement that some rural roads are also dangerous and need to be fixed.
"Up to $100 million will be invested annually in the programme over six years - $60 million more than is usually invested each year in road safety improvements," Mr Bridges said.
"It's forecast that the programme of roading improvements will result in 900 fewer deaths and serious injuries on our roads over the next 10 years.
Road improvements will include realignment of corners, side barriers, median barriers, rumble strips, wide centrelines, road marking and improved signage.
The new funding will only be spent on the State Highway network. Mr Bridges said it would address all known blackspots, some of which had become apparent after recent fatal accidents.
Improvements would be made across the country, including in areas popular with tourists such as Waitomo. Waikato roads will also be a focus, given a higher than normal road toll in the region.
Over the past three years, New Zealand's death toll has risen steadily from 253 in 2013 to 320 last year.
That has alarmed Labour's transport spokeswoman Sue Moroney, who has questioned whether a "cash-strapped" police force has enough resource to target serious driving offences.
Ms Moroney has pushed for a review of the road safety strategy to find out what more could be done. One aspect she would like investigated is any link between heavy vehicles and road safety.
