Tuley-Tillman was charged with three felonies in October.
Tuley-Tillman announced his decision on Twitter on Saturday.
The redshirt sophomore was dismissed from the Michigan football program in September due to “conduct unacceptable for a Michigan student-athlete.”
The following month, Tuley-Tillman was charged with two counts of capturing/distributing an image of an unclothed person and one count of using a computer to commit a crime after allegedly filming a sexual encounter with a woman without her consent.
Tuley-Tillman will be eligible to play as a graduate transfer immediately and has two years left of eligibility remaining.
His pretrial hearing is scheduled for Feb. 8.
Washington State finished 9–4 last season.