Coach Chris Petersen said at Pac-12 media days Thursday that Miles will miss the Aug. 30 game.
Wide receiver Damore'ea Stringfellow, who has since left the team, pleaded guilty to two counts of assault and one count of mischief. Miles was not charged.
Miles, a sophomore, will be one of three quarterbacks competing to replace Keith Price. Redshirt sophomore Jeff Lindquist and redshirt freshman Troy Williams split snaps during spring practice while Miles was suspended from all team activities.
"We thought it was appropriate that he would miss the first game as well," Petersen said while speaking at Paramount Studios. "I'll tell you, he missed all of spring ball, he missed every meeting, everything. He has already been through a lot, just that alone to be put behind the eight ball."
Miles is the only quarterback on the Washington roster who has started a game. He was 15 of 24 for 162 yards and one touchdown in a 69-27 win at Oregon State last season while Price was injured. Petersen, set to begin his first season at Washington after going 92-12 in eight seasons at Boise State, said Miles has learned from what happened.
"He has done everything right, without question, or he wouldn't be with us," Petersen said. "Guys make mistakes. We all know that, especially in that age group."
Stringfellow would have been allowed to return to the Huskies, Petersen said, but announced in May he would transfer. Stringfellow chose Ole Miss after initially committing to Nebraska.