Specialist Sabrina Harman, the last of nine soldiers to be tried over the abuse, was convicted on six out of seven counts against her, including charges of maltreatment of detainees, conspiracy to maltreat detainees and dereliction of duty.
She now faces up to five-and-a-half years in jail.
Harman, 27, is credited with engineering one of the most famous images from Abu Ghraib, showing a hooded inmate in rags standing on a box with electrical wires attached to his hands.
She is also seen posed behind a pyramid of naked Iraqi prisoners and, in another image, giving a thumbs-up signal in front of a corpse wrapped in plastic.
She was cleared on one charge of mistreatment by photographing and filming prisoners forced to masturbate at the jail.
“The substance of it is that based on the verdict, the maximum sentence that could be judged against her would be five and a half years versus the six and an half years, had she been shown guilty on all the specifications,” base spokesman James Wittmeyer told AFP in a brief telephone interview.
Harman is a former pizza restaurant manager from outside the US capital.
Mr Wittmayer said Harman showed no emotion as the verdict was read.
Under existing military rules, the verdict will be automatically appealed.
Like most other soldiers involved in the Abu Ghraib abuse scandal, Harman claimed she had been under pressure from military intelligence officers to conduct the abuse, who wanted the inmates “softened” before their interrogation in order make them more cooperative.
“Sleep, food, clothes, mattresses, cigarettes were all privileges and were granted with information received,” she was quoted as describing the rules allegedly introduced at the prison by US military authorities.
The verdict marks the eighth time a US soldier has been convicted or voluntarily pleaded guilt in the Abu Ghraib scandal.
Six others have reached plea bargain agreements with military prosecutors, while Specialists Charles Graner, the presumed ringleader, received a 10-year sentence.
Brigadier General Janis Karpinski, commander of the military police unit in charge of Abu Ghraib, was relieved of her command, reprimanded and demoted to colonel.