David Littleproud will lead the Nationals following a marathon three-way leadership contest in Canberra on Monday morning, and is expected to define the party's direction after the Coalition's federal election defeat.
Nationals NSW senator Perin Davey was elected deputy for the party in a separate three-way battle for the role.
The party meeting began at 10am with MPs and senators filing out of the room more than two hours later.
"This is the proudest day of my professional life," Mr Littleproud said following the meeting.
"I'm proud to say that my team ... will work collectively together to strive for that."
Former party leader Barnaby Joyce, deputy David Littleproud and former veterans affairs minister Darren Chester jostled for the top job, which the Nationals declare vacant after each election.
Former leader Michael McCormack confirmed late on Sunday he wouldn't be throwing his hat into the ring.
Mr Joyce wanted to retain the leadership after the Nationals emerged from the May 21 election loss still holding all of its lower house seats.
But there was a push to oust Mr Joyce, whose unpopularity in the inner-cities is being blamed for contributing to the defeat of several moderate Liberals to so-called "teal" independent candidates.
One of the vanquished moderate Liberals, Trent Zimmerman, said when weighing up whether to keep Mr Joyce the Nationals needed to decide if it wanted to return to government with the Liberals.
"It's pretty small comfort that you've retained all your seats when you see others falling," Mr Zimmerman told ABC's RN Breakfast.
Mr Zimmerman, who was among the loudest voices inside the Liberals calling for stronger climate action, said National senator Matt Canavan's mid-campaign comment that the pursuit of net zero was "dead" was "one of the killer moments for us".
"Even though the [former] Prime Minister affirmed the government's policy, there was just an underlying suspicion that at the end of the day, people like Canavan, and the hesitation that Barnaby Joyce had along the process would in some way prevail if we were elected," he said.
Mr Littleproud's elevation to the top job is seen as a meteoric rise for the former rural banker, who only entered the Federal Parliament in 2016.
The Member for Maranoa was coy about the leadership contest when he was approached by reporters after touching down in Canberra late on Sunday.
Mallee MP Anne Webster last week nominated for the deputy's position, telling ACM: "I didn't put my hand up for political representation to warm the seat".
As a former social worker and not-for-profit executive who has a PhD, Dr Webster believed she had the mix of skill and experience to help steer the Nationals toward the next election.