"The US Department of State has made a determination approving a possible Foreign Military Sale to the government of New Zealand for MH-60R Multi-Mission Helicopters and related equipment," the department said in a statement on its website on Friday.
The US under President Donald Trump has been pushing allies in Europe and the Asia-Pacific to boost military spending.
NZ, a close ally of neighbouring Australia, is increasingly deploying across East Asia in support of Western militaries and their partners amid China's rapid military rise.
"The proposed sale will improve New Zealand's capability to meet current and future warfare threats by providing greater security for its critical infrastructure," the US statement said, adding NZ would "use the enhanced capability to strengthen its homeland defence".
The purchase of the Seahawk helicopters, made by Lockheed Martin's Sikorsky unit, is part of a 2025 plan by New Zealand's centre-right government to boost defence spending by NZ$9 billion ($5 billion) over four years and almost double spending to two per cent of gross domestic product in eight years.
Wellington allocated $NZ1.58 billion ($916 million) in May in new defence funding as the island nation upgrades its forces.
Prime Minister Christopher Luxon said on Saturday the government remained committed to lifting defence spending after "30 years of underinvestment in defence forces in New Zealand".
"We've moved from a benign environment to a much more globally strategically competitive environment," he said in televised remarks from Noosa, in Queensland, where he is attending an annual bilateral meeting with his Australian counterpart Anthony Albanese.
"It's entirely appropriate that we double our defence spending."
