Funding next year will rise to $NZ5.8 million, compared to just $NZ1.3 million spent last year, according to the minister's office.
No people smuggling boat has ever made it to New Zealand, partly owing to the country's remoteness.
"We do know New Zealand has been targeted by people smugglers and that the risk of that targeting has increased in recent years," Lees-Galloway told reporters.
"It's a treacherous and dangerous journey .. We want to be vigilant and be sure people are not tempted to put their lives at risk."
In a 2018 trans-Tasman stoush over Australia's deportation regime, Australian Home Affairs Minister Peter Dutton said New Zealand didn't "contribute really anything to the defence effort" towards stopping boats.
Lees-Galloway said he had met Dutton twice last year and discussed regional efforts to curb people smuggling, but that no pressure had been applied by the Australian government.
Foreign Minister Winston Peters also said he had fielded no request from Australia, while Prime Minister Jacinda Ardern told reporters the funding did not reflect a change in New Zealand's policy stance.
"New Zealand has always focused on point of departure to stop people from losing their lives. Usually that's through things like information campaigns," Ardern said.
New Zealand's government, meanwhile, is also spending about $NZ140m over five years to increase its annual refugee quota from 1000 people to 1500.