The three were found guilty of beating and harassing prisoners at Camp Bucca in southern Iraq during the US-led war against the country, said spokesman Lieutenant-Colonel Vic Harris on Monday.
The three soldiers had been sent back to the United States after months of investigations led to their administrative discharge by Brigadier-General Ennis Whitehead III, the acting commander of the 143rd Transportation Command, said Harris.
The soldiers were under non-judicial punishment. This meant a jury did not try the case and the defendants did not have to serve time in jail, said Harris. The army had previously said the three faced up to 25 years in jail if convicted of all charges.
The three were named as Master Sergeant Lisa Girman, 35, Staff Sergeant Scott McKenzie, 38 and Specialist Timothy Canjar, 21.
"The charges stem from an incident last year when prisoners were being moved. Master Sergeant Girman, who was the senior person and in charge, was charged with physical abuse of Iraqi detainees," said Harris.
Girman was found guilty of knocking a prisoner to the ground, repeatedly kicking him in the groin, abdomen and head and encouraging her subordinate soldiers to do the same, said army spokesman Lieutenant Colonel Gregory Julian in Atlanta.
Some Iraqi POWs have died
while in occupation custody
McKenzie was found guilty of dragging a prisoner by his armpits across the ground, holding his legs apart and encouraging others to kick him in the groin. Other US soldiers kicked him in the abdomen and head, threw the prisoner to the ground and stepped on his injured arm.
Canjar was found guilty of maltreatment of a prisoner by holding his legs apart while others kicked him in the groin and violently twisting his already injured arm.
McKenzie and Canjar also were convicted of making false sworn statements to army investigators.
The soldiers claimed they acted in self-defence.
These are not the first charges of occupation troops abusing Iraqi POWs.
In July, two British soldiers were ordered out of Iraq after allegations that prisoners of war were beaten up, according to London's Defence Ministry.
Military police had also questioned a British soldier in custody after photographs emerged showing troops allegedly torturing Iraqi POWs.
One photograph showed an Iraqi POW gagged and bound, hanging in netting from a fork-lift truck driven by a British soldier.
In June, the London-based human rights watchdog Amnesty International, said it had evidence that the US violated international law by subjecting Iraqi prisoners to "cruel, inhuman or degrading" conditions.