The sentence is the longest handed down by a U.S. military court for crimes committed in Iraq.
Twenty-four-year-old Sergeant Paul E. Cortez testified that he was among five soldiers who plotted the rape and murders in Al-Mahmudiyah, south of Baghdad, in March 2006.
Cortez was convicted of conspiracy to rape, committing rape, four counts of murder, and other charges. Under military law, he'll be eligible for parole in 10 years. By pleading guilty, he avoided the death penalty.
Defense lawyer William Cassara called the sentence "an appropriate sanction" for Cortez's crimes.
Cortez is the second U.S. soldier to plead guilty in the case. Under the terms of his plea agreement, he agreed to testify against three others still facing prosecution.
In emotional testimony, Cortez admitted he was one of five soldiers from the prestigious 101st Airborne Division who plotted the rape while they were drinking alcohol and playing cards at a traffic checkpoint. He said they targeted 14-year-old Abir Kassem Hamza al-Janabi because her father was the only man in the house.
Cortez told the military court that alleged ringleader, Private Steven Green, who still faces trial, took the girl's mother, father, and 6-year-old sister into a bedroom and shot them. Cortez said he and Specialist James Barker took al-Janabi to the living room, where they raped her. Cortez said Green also raped al-Janabi.
Barker avoided the death penalty as part of his own plea bargain in November. He was sentenced to 90 years in prison and also agreed to cooperate in the prosecutions of the other three men.
Cortez said the soldiers tried to cover up their crimes by burning the girl's body and their own clothes and throwing the murder weapon -- an AK-47 -- into a canal.
Cortez wept as he apologized for his role in the rape and killings. He told the judge he could not explain why he took part.
A psychologist testified that Cortez and the others likely suffered stress brought on by fatigue and trauma.
The case is the second high-profile incident involving soldiers from the 101st Airborne. Three 101st soldiers pled guilty to the murder of three Iraqi detainees during a raid north of Baghdad in May 2006.
(compiled from agency reports)