Iraq's judiciary has sentenced 14 people to death over the 2014 Camp Speicher massacre.
Baghdad's Central Criminal Court issued the verdict on Thursday under Iraq's antiterrorism law.
More than 1,700 unarmed air force recruits, mainly Shiite, were killed in the massacre as ISIS swept across Iraq.
The killings were one of the worst attacks by the terrorist group and became a symbol of its brutality.
Dozens have already been sentenced to death for taking part in the attack at the former US base, near the city of Tikrit.
In June 2021, nine men were handed the death sentence over links to the massacre. They had confessed to their involvement in the killings, the judiciary said. Thirty-six men were hanged in 2016 over the attack.
Baghdad has sentenced hundreds of people to death for terrorism links since declaring the defeat of ISIS in 2017, and has carried out mass executions at Nasiriyah prison, the only facility in Iraq to carry out capital punishment.
Because executions require presidential approval, a relatively small number have been carried out.
A UN team established to investigate ISIS actions in Iraq and Syria found that seven types of war crimes were committed during the massacre.
Soldiers at the base were ordered to change into civilian clothes and were later captured by ISIS militants, who herded them to the banks of the Tigris river and shot them dead.
Numerous mass graves were found and excavated.
Authorities in Lebanon detained the grandson of Saddam Hussein in August over his alleged involvement in the attack.
An Interpol warrant was issued for his arrest when he was stopped in the city of Jbeil. He was extradited to Iraq in November.
Human rights groups have raised concerns over Iraq's detention and prosecution of terrorist suspects.
Amnesty International has accused of Iraq's judiciary of holding "unfair trials" and extracting confessions through torture. It described the 2020 execution of 21 people convicted of terrorism as “an outrage."