The 6-foot-10 Canadian native made a visit to the school shortly before playing with the Canadian national team over the past few weeks.
Wiltjer spent the past two seasons at Kentucky and averaged 10.2 points this past season. However, with another loaded class coming into Lexington, Wiltjer decided to go elsewhere in search of a significant role.
Wiltjer will sit out this season and be eligible in 2014-15 for Mark Few and the Zags.
The Wildcats lost guard Ryan Harrow from last season's team when he transferred to Georgia State. Freshman Archie Goodwin declared for the NBA draft. But the Wildcats bring in a top guard tandem in Aaron and Andrew Harrison, who are expected to start for the team, tabbed as the preseason No. 1 by many media outlets.
Information from ESPN.com's Andy Katz was used in this report.