Following O'Brien's departure to the NFL on January 1, 2014, Johnson was named interim head coach. Johnson departed Penn State after 18 years to become an assistant head coach and defensive line coach at Ohio State later that month. Johnson had a significant impact on Penn State football during his tenure as a coach. He is one of only three coaches in program history with 100 or more wins (O'Brien being the other). Under Johnson, Nittany Lions football reached the postseason for the first time since 1999. He also helped recruit several high-profile players to campus including Michael Bennett, Marcus Allen, and Brandon Short. In October 2013, it was announced that Johnson would not return as the team's defensive line coach following the season. He signed a five-year contract worth $2.5 million with Ohio State in February 2014. During his time at Penn State, Johnson went 82-28 (.746 winning percentage). He arrived at Penn State in 1994 after two seasons as an assistant coach at Temple. Before coming to State College, he served as the defensive ends coach at Boston College from 1992 to 1993 and at Navy from 1990 to 1991. Johnson played college football at Army where he was a four-year letterwinner and starter at defensive end. He finished his career with 43 tackles and six sacks.