The court on Thursday found Sergeant Hasan Akbar, a former member of the 101st Airborne Division, guilty by unanimous vote on two counts of premeditated murder and three counts of attempted premeditated murder, officials said in a written statement.
Akbar faces three possible sentences – death, life in prison or life in prison without the possibility of parole.
The sentencing phase of the trial was scheduled to begin on Monday.
The charges stemmed from a nighttime attack at Camp Pennsylvania in Kuwait on 23 March 2003, as soldiers awaited orders to move into Iraq at the start of the war.
Akbar was accused of rolling grenades into soldiers' tents and firing a rifle at those who emerged.
Two officers were killed and 14 soldiers were wounded.
Akbar's mother and military lawyers said he had snapped in the face of relentless ridicule of his Muslim faith and harassment by fellow soldiers.