Johnson was born in Indianapolis, Indiana. He attended Franklin Jimmy young pdf forex High School in Indianapolis, where he played for head coach Mark James. Tall for his age, Johnson played on the B-team in the 7th and 8th grade. He finished his senior year averaging 20.
1 rebounds a game for the Flashes. Considered a four-star recruit by Rivals. Johnson was listed as the No. 9 power forward and the No. 42 player in the nation in 2007.
2 blocks a game, for which, he was named a First-Team All-Big Ten selection as well as to the Big Ten All-Defensive Team along with teammate, Chris Kramer. He also led the conference shooting 54 percent from the field. Johnson considered entering the 2009 NBA draft, but made a verbal commitment to return for the junior year. Johnson, along with teammate E’Twaun Moore, entered the 2010 NBA draft, but withdrew and returned to school after scouts projected him as a second-round pick. He finished 2nd in school history in career blocks with 263, as well as tallying 854 rebounds. On July 20, 2012, Johnson was traded to the Houston Rockets in a three team deal. He was waived by the Rockets on October 29, 2012.
On November 2, 2012, Johnson was selected by the Fort Wayne Mad Ants with the first pick in the 2012 NBA Development League Draft. On December 28, 2012, Johnson was traded to the Canton Charge in exchange for Luke Harangody. On February 25, 2013, Johnson was traded to the Idaho Stampede. 8th-place finish in the league standings and a spot in the playoffs.