Simon Bridges says he's aiming to surprise in his new role at National's leader, while Paula Bennett has retained the deputy's role.
The pair emerged from today's caucus vote with wide grins after securing the leadership in a vote held behind closed doors.
Bridges said it was an "enormous privilege" to replace Bill English.
Bridges told a press conference he had new ideas and aspirational policies to put to the country in the 2020 election.
"I'm capable of surprises and I'm capable of thinking things through," he said.
"We can't go into the next election with the same plans, but there won't be a full policy review - I don't think we got anything wrong."
Bridges said he would reshuffle the shadow cabinet but wouldn't say who the finance spokesman would be.
He said Steven Joyce, one of the unsuccessful leadership candidates and former finance minister, would have "a strong role" as would the others who stood against him - Judith Collins, Amy Adams and Mark Mitchell.
"It's about keeping experience and bringing through fresh talent," Bridges said.
"We're up for this. The caucus is united, we are aspirational, confident and outward looking.
"There are 56 of us and you're going to be seeing a lot of us and hearing a lot from us."
Voting details weren't released but it was a tight race. Bridges said it took three ballots before he had a clear majority.
Bennett was challenged for the deputy leadership, but the party didn't reveal who stood against her.
Earlier, he said in a statement: "My focus as leader will be ensuring we build on those policies to improve the lives of New Zealanders," he said.
"Our caucus has an incredible depth of talent and abundant energy which is why we continue to enjoy so much support. New Zealanders believe in our vision for New Zealand and in our team.
"My job as leader will be to hold the Jacinda Ardern-Winston Peters coalition to account."
#BREAKING National’s new Leader is Simon Bridges MP.
Posted by New Zealand National Party on Monday, 26 February 2018
Bridges becomes the first Maori leader of the National Party, along with Bennett, who also has Maori heritage, political commentator Bryce Edwards noted.
Bridges replaces Bill English, who resigned on February 13. He will leave Parliament this week, after two stints as National's leader and 10 months as prime minister after Sir John Key quit.
Judith Collins was the first to announce she would run for leader, followed by Amy Adams, Simon Bridges, Mark Mitchell and Steven Joyce.
The first challenge for Bridges will be to unify the caucus after the intense two-weeks leadership contest.
That will be done partly through a re-allocation of roles in a reshuffle, which can be expected as early s this week.
All leadership contenders can expect to have prominent roles in the new lineup.
The biggest issue will be who gets finance, held for the past year by Steven Joyce.
Bridges will be straight into their work - appearing in Parliament at 2pm today to lead National's questions to Prime Minister Jacinda Ardern.
Performance in the House is not considered the most important part of the leader's role but it is crucial to maintaining morale in the party.
National Party president Peter Goodfellow has congratulated Bridges on his appointment.
"Simon will be a fierce opponent for the Coalition Government, and I would expect nothing less," he wrote in an email.
"I am proud to be the president of a strong and united party. Together with Simon and our whole National team, we will continue to hold this government to account until the next general election, and earn the right to re-take the government benches."
After 27 years in Parliament, Bill English will deliver his valedictory address on Thursday.
English took over the leadership for a second time, after the sudden resignation in late 2016 of successful Prime Minister John Key who won three consecutive elections.
National was the highest polling party at the 2017 election – 44.4 per cent compared to Labour's 36.9 per cent – but failed to get a fourth term because New Zealand First elected to form a coalition with Labour.
• Politics: MP for Tauranga, first elected in 2008 replacing National MP Bob Clarkson. Former Minister of Economic Development, Transport, Energy, Labour, Communications and former Leader of the House. Joined Young Nationals aged 16. Stood for deputy leader in 2016 against Paula Bennett.
• Work: Previously Crown prosecutor in Tauranga.
• Family: Raised in Te Atatu, West Auckland, the youngest of six children. Father was a Baptist minister, mother was a primary school teacher. Ngati Maniopoto. Met his wife, Natalie, at Oxford University. Three children, two boys and a daughter who was born in December.
• Education: Former head boy at Rutherford High, where former Labour minister Chris Carter was one of his teachers. BA and LLB (Hons) from Auckland University, Bachelor of Civil Law from Oxford University.
• Voting: Voted against same sex marriage but says now the law is working well and would not change it. Voted against first reading of euthanasia bill.
The National caucus met today behind closed doors to select the new leader, who required the support of at least 29 of the party's 56 MPs. The actual voting numbers are not revealed to caucus.
Each candidate presented a final five-minute pitch to their colleagues at today's meeting.
Today's outcome spells the end of the John Key and Bill English era – an era of unprecedented high popularity for National, including three terms in power from 2008-2017.
Bill English arrived at Parliament earlier today - for his last few hours in the job - keeping tight-lipped about the process to replace him.
He plans to pack up his office, go to a temporary office and be out of Parliament by the end of the week.
He would not make a prediction or say who he was voting for. But he said the new leader needed to be "patient".
Caucus had handled the process of selecting a new leader well, English said.
"They have been civil, they have been respectful, they have gone about it competently and that is a great start for a new leader."