He announced his departure on Instagram Monday morning saying, "I will no longer be continuing my career at the University of Washington."
Sources told ESPN.com on Monday evening that Gardenhire's departure was due to his decision to not take a university ordered drug test.
A starter last year, Gardenhire was a backup cornerback and a big special teams contributor this season for the sixth-ranked Huskies. He tallied 13 tackles, one sack, one interception, two pass break ups, one forced fumble and one recovered fumble.
He will not play against Washington State this Friday in the Apple Cup.