A statement by Justice Minister Hassan al-Shimmary said the men had been found guilty of "carrying out heinous terrorist crimes against the Iraqi people," China's Xinhua News Agency reported.
Among those executed was Adel al-Mashhadani, former head of the Sahwa militia, a Sunni paramilitary group. He was arrested in 2009 for alleged sectarian killings of Shiites.
The executions were carried out Sunday despite pleas from the U.N. Mission, the European Union and international rights groups for Iraq to end the use of the death penalty.
Iraq suspended the death penalty in June 2003, but reinstated it in August 2004, saying it would curb widespread violence in the country.