As a freshman at Wake Forest in 2007-08, Johnson had an instant impact, garnering third team All-ACC honors as a freshman and finishing second in the 2008 ACC Rookie of the Year balloting, as he led the Demon Deacons in scoring and rebounding.
As a sophomore, Johnson again led the team in rebounding, leading the team to a 24-5 record and a #1 ranking during the 2008-09 season.