Mr Rudd pledged to implement his campaign promises as a new era dawned for Australia after Saturday's poll ended nearly 12 years of conservative rule by US President George W. Bush's closest remaining ally in the war in Iraq.
Voters abandoned Mr Howard, 68, who presided over a record economic boom and became Australia's second longest-serving leader, in a humiliating drubbing in which he is also likely to suffer the indignity of losing his parliamentary seat of 33 years.
As the campaign hubris dissipated, Mr Rudd, 50, said his centre-left Labour Party would immediately begin work on fulfilling campaign pledges, which included tackling global warming and withdrawing combat troops from Iraq.
In his first press conference as leader, he also reached out to Australia's traditional allies, offered Mr Bush an olive branch despite policy differences and called for unity at home following a bruising election campaign.
"This is a humbling experience, to be extended the trust and confidence of people right across the country," he said in his hometown of Brisbane, thanking voters and promising not to breach their trust.
"I would also say to those people that we will be a government for all Australians and that I will always govern in the national interest," he said.
Mr Rudd revealed he had spoken to major world leaders on the telephone, including British Prime Minister Gordon Brown, Indonesian President Susilo Bambang Yudhoyono and Mr Bush. "I emphasised to President Bush the centrality of the US alliance in our approach to future foreign policy," Mr Rudd said, adding he planned to visit the United States in 2008 and that Mr Bush had welcomed the trip.
But Mr Rudd refused to say if he had discussed his campaign pledge to withdraw Australia's 550 combat troops from Iraq with Bush, a plan Mr Howard and Mr Bush insisted would be a signal that the "terrorists" were winning the conflict.