Spc Charles Graner, regarded as the ringleader at the centre of the abuse scandal, also received a dishonourable discharge from the US army.
The military jury passed sentence a day after Graner was convicted at a court martial in Fort Hood, Texas.
Graner said he was only following orders to "soften" up prisoners.
The prosecution, however, claimed Graner was the lead abuser and portrayed him as a sadistic bully.
The former military policeman was pictured abusing inmates in a series of photographs which sparked outrage around the world.
'I did what I did'
Before his sentencing, 36-year-old Graner took the stand for the first time to ask for leniency.
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ABU GHRAIB SCANDAL
Sentenced:
Spc Charles Graner Pte Jeremy Sivits Sgt Ivan Frederick Spc Megan Ambuhl Spc Armin Cruz
Facing trial:
Pte Lynndie England Sgt Javal Davies Spc Sabrina Harman  |
Graner told the jury at the Fort Hood army base: "I did what I did. A lot of it was wrong, a lot of it was criminal. I did not enjoy it."
But he said when he complained to superiors he was ordered to do what he was told and to obey military intelligence personnel, who gave orders at the prison.
Asked after sentencing if he had any regret, Graner said simply: "There's a war on. Bad things happen."
Graner's mother, Irma, said her boy was "not the monster he is made out to be," and insisted blame lay higher up the chain of command.
"My son was convicted the day President Bush went on TV and said that seven bad apples disgraced the country.
"You know it's the higher-ups that should be on trial. They let the little guys take the fall for them," she said.
The publication in early 2004 of dozens of photographs showing prisoner abuse at Abu Ghraib prompted global condemnation of US actions in Iraq.
Naked pyramid
Following five days of proceedings, the jury of four officers and six enlisted soldiers took about five hours to reach their verdict.
They found Graner guilty of multiple charges of assault, mistreatment of prisoners and conspiracy.
Among the charges, Graner was accused of stacking naked detainees in a human pyramid, and later ordering them to masturbate while other soldiers took photographs.
An independent commission ruled in August 2004 that blame for the abuses lay almost totally with the soldiers who ran the jail, but faulted Defence Secretary Rumsfeld and colleagues for not providing adequate leadership to prevent the abuse.
The BBC 's Nick Childs at the Pentagon says the Bush administration has all along maintained that the Abu Ghraib abuses were the result of rogue elements there.
Critics still maintain the soldiers who have been charged so far are scapegoats and that responsibility goes right to the top of the administration.