The Government is buying four Defence Force aircraft off the United States for $2.336 billion.
The Boeing P-8 Poseidon aircrafts are designed for "long-range anti-submarine warfare, anti-surface warfare, and intelligence, surveillance and reconnaissance missions."
They have two engines and are 39 metres-long, with a 37-metre wing span.
Australia purchased eight P-8 Poseidon in 2016. The aircraft are also used in India, the United States and the United Kingdom.
The four new aircraft will replace the six ageing P-3K2 Orion maritime patrol aircraft that have been in operation since the 1960s.
Defence Minister Ron Mark said the aircraft would be used to keep a "close eye" on whaling and fishing and for collecting intelligence.
"It is the only option that delivers all the capabilities," Mr Mark said at the post-Cabinet press conference on Monday.
"I was a P-8 sceptic - I put my hand up on that one - but no matter how I looked at this case, the aircraft stacks up on its own."
The P-8s will be delivered in 2023, and the number 5 squadron that operated the Orions will move to Ohakea Base.
A strategic defence paper released last week warned of the increasing influence of China. It said New Zealand is facing complex threats not seen before, including meddling in democracy, climate change and populism causing nations to look inward.
National's Defence spokesperson Mark Mitchell backs the Government's decision.
"The previous Government had put a lot of work into this, and had the process well advanced, so it's pleasing to see this Government has finally made the right decision," he said.
"The procurement of the P-8s sends a positive signal to our allies and partners, showing that we will remain a capable Defence Force, and are well equipped to play our role on the international stage."
But The Green Party's Golriz Ghahraman said the Greens wouldn't have chosen to buy such expensive planes.
"We just follow Australia, the US, the UK down the path of building up bigger and bigger armies with focus on war capability. [We need to] more forge our own path," Ms Ghahraman told Newshub.
"We strongly believe our Defence Force needs to move away from that."
Last week, Newshub revealed more than half the Air Force's Hercules aircraft are grounded for maintenance at any one time.