Bruins coach Jim Mora announced the decision Tuesday.
McDonald was the Bruins' starting safety the past two seasons. He finished third on the team with 79 tackles last season while starting 13 games, but wasn't allowed to play in the Holiday Bowl after violating team rules.
McDonald is the son of longtime NFL defensive back Tim McDonald and the brother of former Southern California safety T.J. McDonald.
Mora also says receivers Jerry Rice Jr. and Ricky Marvray will transfer for their senior years of eligibility after graduating from UCLA.
Rice is the son of Hall of Fame receiver Jerry Rice. He has caught nine passes for 69 yards in three seasons at UCLA.