The Coalition swept to victory in the general election in Australia on Saturday.
Liberal Party leader Tony Abbott claimed victory at about 10.15pm (AEST), 40 minutes after Labor prime minister Kevin Rudd publicly conceded.
At this stage, the Coalition has 81 seats and Labour has 51.
''The time for campaigning has passed, the time for governing has arrived. I pledge myself to the service of our country," Mr Abbott said in a victory speech at the Four Seasons Hotel in Sydney.
"I now look forward to forming a government that is competent, that is trustworthy, and which purposefully and steadfastly and methodically sets about delivering on our commitments to you, the Australian people.
"In three years, the carbon tax will be gone, the boats will be stopped, the budget will be on track for a believable surplus and the roads of the 21st century will finally be well underway.
"And from today, I declare that Australia is under new management and that Australia is once more open for business."
He noted that "hundreds of thousands" of people had voted for the Coalition for the first time in this election and told them his government "will not let you down".
"A good government is one that governs for all Australians - including those who haven't voted for it," Mr Abbott said.
"A good government is one with a duty to help everyone to maximise his or her potential, Indigenous people, people with disabilities and our forgotten families, as well as those who Menzies described as lifters, not leaners," he said.
"We will not leave anyone behind."
With 76% of the vote counted, the ABC predicted the Coalition would win 89 seats, 17 more than in the 2010 federal election, and Labor 57. Coalition gains centre around New South Wales, Victoria and Tasmania.
So far, the Coalition has 81 seats and Labor 51.
The Coalition has so far won 53.5% of votes on a two-party preferred basis, a swing of 3.6% in its favour.
Labor had a primary vote swing against it of around 4.5%.
However, the balance of power in Senate likely will remain in minority party hands, although the final composition remained uncertain on Saturday night as counting continued.
In Queensland, the Coalition failed to win any Labor seats and billionaire businessman Clive Palmer appears close to claiming the seat of Fairfax in the Lower House.
The ALP was the first two-term federal government to be thrown out of office since Gough Whitlam's regime in 1975.
What's ahead for new PM
Mr Abbott on Saturday night repeated campaign pledges to get the budget on track to surplus, scrap the carbon tax and "stop the boats".
The ABC reports these may be challenging promises to fulfil and Mr Abbott will need to show voters swift signs of success in those areas to avoid political damage.
He believes cutting red and green tape, having a firm fiscal strategy and supporting private enterprise will help reverse what he calls a "budget emergency".
The incoming prime minister characterised the election as a referendum on the carbon tax and has promised to begin work on legislation to repeal it on the first day of government.
However, until mid-2014 the Senate will remain under the control of Labor and the Greens, which have both indicated they would block a move to scrap the carbon tax.
The ABC reports Mr Abbott has left open the option of a double dissolution election if his plan faces opposition in the Senate.
Abbott doubters foolish: Howard
Mr Abbott is Australia's 28th prime minister.
Former prime minister John Howard said anyone who thought he was un-electable has been proven foolish. He said Mr Abbott will do a fantastic job as prime minister.
"All those ridiculous people who said he was unelectable should understand how foolish they were to underestimate him," Mr Howard told the Seven Network.
"I can't speak too highly of what a wonderful job Tony Abbott has done."
AAP reports Mr Howard said Mr Abbott and his team would serve the country well.
"Tony Abbott will do a fantastic job, we will look after the security of this country, we will look after the public money," he said.
He said Labor's defeat was deserved:
"This has been a very unstable, incompetent government," was his verdict.
Mr Abbott began his first day as the nation's leader with an early morning bike ride accompanied by friends and breakfast at his home in Sydney before a series of briefings with public servants.
He became Australia's 28th prime minister after a decisive swing toward the Coalition in the federal election.
Mr Abbott on Saturday night declared Australia under new management and open for business in his victory speech, pledging to create a competent, trustworthy government.
The ABC reports he is likely to name a cabinet very similar to his shadow front bench.
AAP reports Mr Abbott's wife Margie was up early, too, saying she was "feeling fine".
"Life goes on and I've been out to get some early morning groceries and hopefully the day will be as normal as possible," she told the Sunrise programme on the Seven Network.