After days of frenzied speculation and a near three-hour caucus meeting in Wellington on Wednesday, Mr Luxon emerged victorious and vowed to win the November 7 election.
"There was a confidence vote in my leadership this morning at our caucus meeting, and I have the full support of our caucus," he said.
"Our caucus is united, and it is determined to win this election."
The result follows a similar vote in April, when Mr Luxon also brought on a leadership vote in himself and won.
The margin of the vote is not known, and is usually a tightly-held secret by the National party.
The vote is an astonishing victory for Mr Luxon, who has endured poor personal polling and several high-profile gaffes in recent weeks, but prevailed.
Most political observers tipped a successful spill, with former defence minister Wayne Mapp saying Mr Luxon's calculus was off when he called the meeting.
"If he wanted to stay in the job he should have just toughed it out," Mr Mapp told Radio NZ.
Radio NZ political editor Jo Moir said the 56-year-old's leadership was "hanging by a thread," while NZ Herald political editor Thomas Coughlan - who broke the story of increased discontent on Monday - said Mr Luxon surviving was "incredibly unlikely".
Key ally Mark Mitchell, the police minister, said he sat with Mr Luxon until 11pm on Tuesday night "making sure he's in the strongest possible position".
"Discussions will be about calling out (disloyal MPs) and making sure there is loyalty to our leader," hetold Newstalk ZB.
"He's been a great prime minister during very difficult global times ... I'm behind him 110 per cent."
There were no confirmed candidates to replace Mr Luxon, though education minister Erica Stanford was reported as a possible replacement.
Ms Stanford was pictured behind Mr Luxon at his 90-second press conference after the caucus meeting in a likely show of loyalty.
This week's crisis is made even more remarkable by the fact that National is currently in an election-winning position.
The conservative party governs in coalition with the support of free-marketers ACT and populists NZ First.
Almost every poll in recent months shows a decent lead for that right bloc over a left bloc of opposition parties Labour, the Greens and the Maori Party.
The key factor behind National's implosion appears to be their own cratering support, from 38 per cent at the 2023 election to a polling average of about 29 per cent.
Many argue National's popularity slide is down to Mr Luxon, who has shocking personal favourability ratings.
In 2023, Kiwis were enthused by the former executive's business credentials and voted him in after he campaigned to turn around the economy and reduce government debt.
Mr Luxon has failed to land either pledge, and has rubbed many the wrong way with a series of elitist or out-of-touch comments.
A poll released by TVNZ on Wednesday confirmed Mr Luxon's poor support: just 17 per cent of Kiwis named him as their preferred prime minister, though he led allcomers with Opposition Leader Chris Hipkins on 15 per cent.
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