The youths entered surprise guilty pleas at the courthouse in Wetaskiwin, Alberta on the day their trial was scheduled to begin.
Ethan Yellowbird was sleeping in his grandfather's house on July 11, 2011 when bullets sprayed the home at 3:30 a.m. in a drive-by shooting. He died after being shot in the head.
The three teens were arrested in January.
According to the agreed statement of facts, the oldest youth, who was 17 at the time, used a rifle to fire the first shot over and above the house. He handed the gun to the other boys, then 16 and 13, who fired two shots each at the home.
"One of the shots fired at the house hit Ethan Yellowbird," the court document states.
The trio will return to court for sentencing on Nov. 21. The Crown intends to seek the maximum penalty available under the Youth Criminal Justice Act — two years' custody and one year of community supervision.
RCMP believe the teens have gang affiliations but the Crown did not speculate on a possible motive for the shooting.
The young boy's death moved the community of Hobbema to take action against gang violence.
Residents supported a bylaw that will let council banish troublemakers from the reserve.