He played college football for the Arkansas State Indians and was selected by the Minnesota Vikings in the second round of the 2008 NFL draft.

As a sophomore in 2000 he had helped Rison High School win the state football championship with a victory over Shiloh Christian which was coached by Gus Malzahn.

His best season came in 2007 as he earned third-team All-American, first-team All-Sun Belt Conference and was the leagues Defensive Player of the Year after recording 94 tackles and six interceptions.

He finished his career playing in 46 games, starting all of them, with a Sun Belt Conference record 363 tackles, 13 interceptions, and four forced fumbles.

This interception was made in the end zone against the St. Louis Rams who were on the Vikings 9 yard line before Johnson killed their long drive.

Johnson's father, Alvin Robertson, played ten years in the NBA for the San Antonio Spurs, Milwaukee Bucks, Detroit Pistons, and Toronto Raptors[3] His mother, Patricia, ran track for the University of Arkansas.