Ms Bligh has become the country's first woman to be elected state premier
Australia has its first elected female state premier in its history after a vote in Queensland.
Anna Bligh led Prime Minister Kevin Rudd's centre-left Labor government to victory in the state election.
She took over in September 2007 after the mid-term retirement of veteran Labor Premier Peter Beatie.
A swing to the Liberal National Party was not enough for its leader, Lawrence Springborg, and he has conceded defeat and sent her his congratulations.
But Mr Rudd will probably think twice about holding an early national election given the nearly 4% surge in support for the Liberal National Party, say correspondents.
"Queenslanders, thank you," Ms Bligh said as she claimed victory.
Opposition leader Lawrence Springborg was gracious in defeat
"You have given me a mandate to protect your jobs and build a stronger Queensland, and I am ready for the task."
The Labor Party has been in power in Queensland for 11 years, and Ms Bligh argued that at this time of economic uncertainty it made sense to stay with an experienced government.
She had called an election six months early, insisting that she needed a fresh mandate to deal with an economic slump in Queensland, which is one of Australia's leading mining areas.
Her critics said she was afraid of being punished by voters later in the year as the state's once mighty resources sector suffered in the global downturn.
But her opponent was gracious in defeat. Mr Springborg said: "Premier Bligh ran a very significant and very formidable campaign."
It was the first electoral test for the conservative party, which was formed when the state National and Liberal parties merged last year.
Queensland is one of Australia's more conservative states, so Ms Bligh did not present herself as a feminist trailblazer, says BBC's Nick Bryant in Sydney, stressing her economic stewardship instead.
Another Queensland woman - the far-right politician Pauline Hanson - tried unsuccessfully to mount a political comeback.
Ten years ago, at the height of her popularity, her anti-Asian immigration One Nation party won more than a tenth of the seats in the Queensland legislative assembly.
There have been female state premiers before - in Western Australia and Victoria - but they succeeded to the posts without election, and never won their own mandates.