In all, 56 countries including the United States endorsed a US-initiated statement voicing concern at Iran's arrests and executions of dissidents and calling on Tehran to uphold fundamental freedoms of expression, media and assembly.
"We were able to garner broad cross-regional support for this initiative, from all regions of the world, at a very crucial juncture for the people of Iran," US Ambassador Eileen Chamberlain Donahoe told reporters.
Donahoe, wearing a bright green neck scarf, called the text a "statement of solidarity with the Green Movement inside Iran.
"The brutality and violence committed by the Iranian regime against human rights defenders and peaceful protesters is sickening," she said.
Iran's ambassador, Hamid Baeidi Nejad, backed by Muslim and other allies, initially objected to the text on procedural grounds, but later allowed it to be read out in full by Norway's envoy Bente Angell-Hansen.
The non-binding statement adds to pressure on Iran after the UN Security Council last week extended punitive sanctions against Tehran over concerns that its secretive nuclear energy program is an effort to develop atomic bombs.
The United States joined the Council for the first time last year, after winning election to the Geneva forum set up in 2006.
Dominated by developing nations wary of interference in their own affairs, the Council rarely "names and shames" states. The main exception is Israel, which is regularly condemned for alleged abuses in its occupied territories.
Drawing attention to the human rights situation in Iran is a priority of US President Barack Obama, whose administration has also been focused on the nuclear program, Donahoe said.
"US leadership at the Human Rights Council matters. Without US engagement here, we leave a vacuum of leadership which will get filled by the priorities of others," she said.
"Today's success in the Human Rights Council is a testament to the multiple dimensions of US leadership, as well as the very strong partnerships we have with other leaders throughout the world."
Pakistan, speaking for the Organization of the Islamic Conference (OIC), as well as African and non-aligned countries, backed Iran in the debate. The objection was to Iran's record, a "country-specific situation," being addressed under an agenda item on a landmark human rights meeting held in Vienna in 1993.
"Allowing this to happen ... is leading to a repeat of the practice of the Human Rights Commission where 'naming and shaming' was the name of the game and led eventually to the demise of the Commission," Pakistan's envoy Zamir Akram said, referring to the Council's largely discredited predecessor body.
The United States and Norway had heavily lobbied countries to endorse the statement, saying the one-year anniversary of the violent protests should be marked.
The 2009 post-election street protests, the worst unrest since the Islamic republic was founded in 1979, were put down violently by the Revolutionary Guards. Mass detentions followed. Two people were hanged and scores of detainees remain in jail.
The text voices concern at "events including the violent suppression of dissent, detention and executions without due process of law, severe discrimination against women and minorities including people of the Baha'i faith and restrictions on freedom of expression and religion."
