National has promised $267 million towards commuter rail projects in Auckland and Wellington in its transport policy announcement.
Prime Minister Bill English announced the three-year plan to build new rail lines and to electrify more of the network on Sunday afternoon.
The funding is to provide "reliable, high-frequency and more integrated service for commuters," Mr English said.
He said the scheme would work alongside Auckland's City Rail network, the construction of which is already underway.
In Auckland, National has promised to invest $130 million to electrify the track between Papakura and Pukekohe, while another $100 million goes towards a third main line from Wiri to Westfield, for freight.
"Electrification is a key element of the National-led Government's focus on supporting a cohesive, efficient transport system for Auckland," National's transport spokesperson, Simon Bridges, said.
"Auckland's population growth has meant more commuter trains using the rail network around Auckland and competing with the growing number of freight trains using this important corridor."
Around $37 million goes to Wellington, on top of the $98.4 million promised in the Budget earlier this year.
It'd see an upgrade of bridges and slopes, a full double track on the Hutt Valley Line between Upper Hutt and Trentham, and a third platform for Porirua Station.
The announcement comes hot on the heels of Labour's transport policy, which promised to build light rail from Auckland's CBD to the airport within a decade - three times quicker than National.