Tressel, who coached Michigan State's safeties in 2020 under coach Mel Tucker, will replace Marcus Freeman with the Bearcats. Freeman left earlier this month to become Notre Dame's defensive coordinator.
Tressel, 47, has worked at Michigan State since 2007, serving as co-defensive coordinator from 2015 to 2017 and then as the team's sole defensive coordinator in 2018 and 2019. He came to Michigan State with Mark Dantonio from Cincinnati, where he coached the Bearcats' linebackers and special teams from 2004 to 2006.
Tressel's uncle is former Ohio State head coach Jim Tressel, and he worked alongside Cincinnati coach Luke Fickell at Ohio State in 2002 and 2003. Cincinnati finished No. 8 this past season after winning the AAC and reaching its first New Year's Six bowl since the 2009 season. The Bearcats lost to Georgia in the Peach Bowl to finish 9-1.
Cincinnati's defense ranked eighth nationally in points allowed (16.8 PPG) in 2020 and returns defensive linemen Myjai Sanders and Curtis Brooks, linebackers Joel Dublanko and Darrian Beavers, cornerback Coby Bryant and others.