Army Reservist Charles Graner stood at attention and looked straight ahead without any visible reaction as the 10-member jury read its verdict on Friday. He held his hands tightly clenched.
Because the jury altered one count to a lesser charge of assault, rather than use of force likely to produce death or grievous bodily harm, his maximum sentence was lessened to 15 years from a possible seventeen-and-a-half-years, a prosecution spokesman said.
The jury took less than five hours to reach its verdict.
The verdict came after a five-day trial in which prosecutors depicted Graner as a sadistic soldier who took great pleasure in seeing detainees suffer. He was accused of stacking naked prisoners in a human pyramid and later ordering them to masturbate while other soldiers took photographs.
Graner also allegedly punched one man in the head hard enough to knock him out, and struck an injured prisoner with a collapsible metal stick.
The jury of four army officers and six senior enlisted men rejected the defence argument that Graner and other prison guards were merely following orders from intelligence agents at Abu Ghraib to soften up the detainees for interrogation.
Graner, 36, was convicted of conspiracy, assault, maltreating prisoners, dereliction of duty and committing indecent acts.