Before their release, the prisoners reportedly signed a pledge that they would no longer endanger other Iraqis.
"The treatment was bad at the beginning. Thank God, it was good this year," former detainee Jumaa al-Suwaidawi told Reuters.
Around 350 prisoners were freed from US custody in October this year in a move marking the end of the Muslim month of Ramadan.
About 50 prisoners a day had been freed in recent weeks, Angela Webb, a deputy spokeswoman for US detainee operations in Iraq, told Reuters news agency.
About 6,300 detainees have been released so far this year, she added.
It is estimated that around 25,000 prisoners remain in US custody in Iraq, and more are brought in every week. Many have been held without trial for months.
Thousands of other prisoners are also held in Iraqi jails.
The issue of Iraqi prisoners in US detention remains controversial following the Abu Ghraib scandal which emerged in 2004, when US gaolers were depicted in photographs abusing naked Iraqi detainees at the Abu Ghraib prison west of Baghdad.
Several US military personnel were convicted of charges relating to the abuse, however the only officer charged in connection with the case was cleared on charges of mistreating detainees.