The move, the largest prisoner release to date, followed appeals by Sunni representatives at the stalled constitutional talks to the government to start releasing thousands of prisoners who have been languishing in the jail for months without being charged with a crime.
After a meeting with President Jalal Talabani on Thursday, Sunni negotiator Saleh al-Mutlaq said the president agreed to release many detainees before the 15 October referendum on the constitution.
Al-Mutlaq said hundreds of detainees, most of them Sunni Arabs, were to be set free.
Good citizen pledge
"This major release ... marks a significant event in Iraq's progress toward democratic governance and the rule of law," the US statement said.
"Those chosen for release are not guilty of serious, violent crimes - such as bombing, torture, kidnapping, or murder - and all have admitted their crimes, renounced violence, and pledged to be good citizens of a democratic Iraq."
Abu Ghraib prison, built by Saddam Hussein's government in the 1970s on the outskirts of Baghdad, was retained as a major detention centre by the US occupation authorities after the invasion of Iraq in 2003.
It gained international notoriety after a number of US military personnel were charged with humiliating and assaulting detainees at the facility.