The new UN High Commissioner for Human Rights will be South African judge Navanethem Pillay.
She has been nominated despite initial American resistance over her support for abortion rights.
The UN General Assembly is to meet today to confirm Ms Pillay’s appointment to the high profile role.
UN Secretary-General Ban Ki-moon announced her nomination on Thursday.
In an interview with Reuters, the United States Ambassador to the United Nations, Zalmay Khalilzad, congratulated Ms Pillay on her new job.
“We need a strong voice, we need a credible voice to speak on the issue of human rights issues, one of the key missions of the United Nations and we look forward to working with her,” he said.
He denied the US had formally opposed her nomination.
In 1967 Ms Pillay became the first woman to start a law practice in Natal Province, South Africa, and the first black woman to serve in the country’s High Court.
As a lawyer she defended many opponents of apartheid.
She was elected by the United Nations General Assembly to be a judge at the International Criminal Tribunal for Rwanda, where she served for eight years, including four years as president.
She has written on and practised in international criminal law, international humanitarian law and international human rights law, and more particularly on crimes of sexual violence in conflicts.
In a valedictory speech to the United Nations Human Rights Council in June, former UN High Commissioner for Human Rights Louise Arbour challenged the continued oppression of women and sexual minorities.
“A failure to understand or accommodate diversity has inevitably led to an erosion of the rights of minorities and vulnerable people within a country, and those of individuals who move across borders, including refugees or migrants,” she told the 47-member council.
“Fears and mutual suspicions, engendered by the security environment that has prevailed in the past few years, have exposed minorities to additional risks and abuse.
“The perpetuation of prejudices continue to deny equal rights and dignity to millions worldwide on the basis of nothing more innocuous than their sexual identity or orientation, or their ancestry, in the case of caste discrimination.”
During her time as UN High Commissioner for Human Rights many Muslim and African countries expressed their displeasure at Mrs Arbour’s insistence that gay and lesbian people and women have human rights equal to those of men.
She highlighted the treatment of sexual minorities through her work.
Mrs Arbour said the new state reporting system, known as the Universal Periodic Review, could provide a vehicle for scrutiny of the implementation of rights and norms beyond anything ever attempted by the Commission on Human Rights, the ineffective body that was replaced by the Human Rights Council in June 2006.
The UPR, which began functioning in April, has examined the human rights record of 32 states so far, and will take four years to complete its first round of all the UN’s 192 member states. It illustrates deep divisions on the issue of gay rights.
As part of the second stage of the UPR Tonga was advised to decriminalise sexual activity between consenting adults, recommended by the Netherlands, Canada and the Czech Republic.
However Bangladesh, a Muslim country, told Tonga it should retain a ban on gay sex.
Pakistan has expressed the view that sexual orientation falls outside “universally recognised human rights.”
Last year Mrs Arbour declared her support for the Yogyakarta Principles.
Named after the Indonesian city where they were adopted, the principles were introduced by 29 international human rights experts at a UN Human Rights Council session in Geneva in March 2007.
They refer to the application of international human rights law in relation to sexual orientation and gender identity and address issues such as rape and gender-based violence, extra-judicial executions, torture and medical abuses, repressions of free speech and discrimination in the public services.