Johnson played high school basketball at Hubbard High School where he was a four-year starter. As a junior he averaged 21 points and nine assists per game, although the team finished with an 11–14 record. The following year, however, Johnson led Hubbard to a 21–9 record while winning the regional championship. He achieved all-city honors after averaging 14 points and nine assists per game. Johnson was also rated as one of the top 25 players in the state of Illinois according to Rivals.com.
