The US had previously been critical of the UN Human Rights Council
The United States has been elected to a seat on the UN Human Rights Council for the first time.
The council had been shunned by the Bush administration, which accused it of admitting states with poor rights records and having an anti-Israel bias.
But the Obama administration has reversed its predecessor's policy of boycotting the Geneva-based body.
The US was one of 18 countries elected to the 47-seat council in a vote by the UN General Assembly.
After the vote, the US Ambassador to the UN, Susan Rice, told the BBC America was not blind to the council's flaws.
"Obviously there will always be some countries whose respect and record on human rights is sub-par," she said.
"We have not been perfect ourselves but we intend to lead based on the strong principled vision that the American people have about respecting human rights [and] supporting democracy."
Ms Rice added that the US looked forward to the review of the council's workings due in 2011.
'Era of engagement'
The US was elected unopposed with 90% of the vote because countries agree in advance which of them will stand for election, the BBC's Laura Trevelyan reports from New York.
It is these uncompetitive elections, say critics, which allow repressive countries to get on the council and then use it to block scrutiny of their behaviour.
The Obama administration announced in March that it would be seeking to join the Human Rights Council as part of a broader strategy to create a "new era of engagement" with the rest of the world.
Previously, the US government had accused the council of being hijacked by countries with a strong bias against Israel, and had criticised it for its failure to condemn perceived human rights violations by the Sudanese government in Darfur.
A number of countries whose human rights records have been criticised by the US - including Cuba, Saudi Arabia, China and Russia - are also represented on the council.
The council was set up in 2006 to replace the UN Commission on Human Rights, which had also been dogged by accusations of anti-Israeli prejudice.