Wilcox spent the last two seasons with the Trojans, serving under former head coach Steve Sarkisian. He finished the season after sarkisian was fired, but was not retained when interim coach Clay Helton was promoted to the full-time job.
“During my many conversations with numerous football people that I trusted, one name kept surfacing, Justin Wilcox,” Wisconsin head coach Paul Chryst said. “I am very happy that we were able to get a quality coach like Justin to join our staff. I think he's a great fit for Wisconsin and this program is a great fit for him. His addition makes us better.”
Wisconsin finished last season 10–3, beating the Trojans 23–21 in the Holiday Bowl. Former Wisconsin defensive coordinator was hired by LSU on Jan. 1.