Aggies coach Matt Wells announced the hiring Saturday.
Kotulski was Utah State's defensive coordinator and inside linebackers coach in 2003 and 2004 under Mick Dennehy.
Kotulski was out of coaching last season. He spent the 2014 season at Vanderbilt as defensive coordinator and inside linebackers coach after two years at Stanford as inside linebackers. The former New Mexico State linebacker and center also has coached at Utah, St. Mary's, Bucknell, Holy Cross and Lehigh.