He earned Parade, PrepStar, Football News and USA Today All-America first-team honors as a senior.

Johnson recorded 104 tackles, including 32 for loss, and 17 sacks as a senior for the Knights while also setting school records for career sacks (61), tackles for loss (77), forced fumbles (14), and blocked punts (five).

He also played forward on the basketball team, and in track and field he competed in the shot put and the 100 meter dash.

[2] Projected as a mid-first rounder by Sports Illustrated, Johnson was ranked as the best defensive tackle available in the 2005 NFL draft.

Johnson was traded to the San Diego Chargers on August 31, 2009, for a sixth round pick in the 2010 NFL draft.