Down 12-0 early and 14-6 at the break, the Kiwis ran in five unanswered second-half tries to win 36-14 and deny Samoa a maiden international trophy.
Dylan Brown was man of the match for a third straight game with three assists, again offering hope to long-suffering Newcastle fans ahead of his arrival at the club.
Naufahu Whyte was powerful up front, while Erin Clark capped his breakthrough season with a brilliant outing and the mobile Kiwi pack offloaded at will.
The result also sent Kieran Foran out a winner, with the 35-year-old ending one of rugby league's gutsiest 17-season careers by holding up an international trophy.
It has not been lost on Kiwi players through this tournament that they have almost become the forgotten country in international rugby league.
With all the focus on the rise of Samoa and Tonga, the Kiwis have almost slipped out of the conversation regarding World Cup contenders next year.
But Sunday was a clear reminder that Stacey Jones' men should not be overlooked, especially with Jahrome Hughes set to return for next year's World Cup.
"These guys know differently for us, they are world-class players," Jones said.
"What they do in the middle and having someone like Kieran Foran to get the team around the field. The outside backs, there is some skill in there.
"We went under the radar a little bit, which was good. But you have to take your hat off to Tonga and Samoa with how they go about things."
After outlasting Samoa and thrashing Tonga to make this year's final, the Kiwis had to do it the hard way in the decider.
Both teams' packs battered each other early on, with Payne Haas and Francis Molo going at the Kiwis in an engrossing first half.
Samoa took their chances early, with Jarome Luai sending Brian To'o over for one try and Simi Sasagi claiming a 70-metre intercept for another.
But the signs were there for New Zealand, with Keano Kini dangerous at fullback and Whyte trampling defenders at will at some stages.
And while Whyte scored the Kiwis' only first-half try when Clark went to the line and drew in a defender, the floodgates opened after the break.
Foran and Brown combined to send over Isaiah Papali'i and reduce the margin to 14-12, before a penalty goal brought New Zealand level.
Clark capped a superb year when he barged through three defenders to make it 20-14, before a James Fisher-Harris charge created the space for Brown to send Casey McLean over.
And by the time Papali'i and Charnze Nicoll-Klokstad crossed in the final five minutes, the Kiwis were rocking and Foran was going out a winner.
"It's hard to believe. The boys dug so deep, I knew they would," Foran said.
"I wanted to come in here and try and finish on a high. It's been a tough year (at Gold Coast).
"But to come here and do it with this bunch of boys, it's just the cherry on top."
Samoa were gutsy despite having next to no ball after the break and will welcome more big names back for next year's World Cup, having reached the final in 2022.
"We've been excited the whole time, and made no secret of the fact we're working towards getting to the World Cup and putting our best foot forward," said coach Ben Gardiner.
"I thought this tournament was putting our best foot forward.
"In comparison to where we were in the Pacific Champs (in 2023) and in England last year, we took major steps forward.
"But the reality is ... to allow 30 points to be scored in the second half, you're not going to compete in Test matches."
