Johnson played basketball for four years at East Technical High School in Cleveland, Ohio. As a freshman, he scored 27 points and made a game-winning jump shot with 3.1 seconds left against Lake High School to help his team reach its first state semifinal since 1972. He was considered one of the best freshman in Ohio. In his junior season, Johnson averaged 31.6 points, 7.4 rebounds and 3.5 steals per game, leading East Tech to its third straight league title and a district semifinal appearance. He was named Cleveland.com Boys Basketball Player of the Year and Northeast Lakes Division II All-District Player of the Year by the Associated Press. On May 2, 2016, Johnson decided to reclassify to the 2016 class and forgo his senior year. On the Amateur Athletic Union circuit, he played for the King James Shooting Stars, a team affiliated with NBA player LeBron James. Johnson was a four-star recruit and committed to play college basketball for NC State over offers from Louisville, Ohio State, Washington and West Virginia, among others.
College career
As a freshman, Johnson served as a backup to Dennis Smith Jr., who enrolled a year earlier than expected. On December 16, 2017, during his sophomore season, he was suspended indefinitely and briefly jailed for felonious assault charges but was cleared to return on January 11, 2018. He averaged 8.9 points and an Atlantic Coast Conference-leading 7.3 assists per game as a sophomore. On December 19, 2018, Johnson set career highs with 27 points and five three-pointers in a 78–71 upset of seventh-ranked Auburn. He missed three games as a junior with a back injury. Johnson averaged 12.6 points and 4.2 assists per game as a junior, shooting 42.2 percent from behind the arc. After the season he declared for the 2019 NBA draft but ultimately returned to NC State. He injured his ankle in practice and missed the first game of his senior season, an overtime loss to Georgia Tech. Johnson hit a halfcourt buzzer beater to defeat UNC Greensboro 80–77 on December 15, 2019. On December 22, Johnson recorded a triple-double of 11 points, 10 rebounds and 10 assists in a 83–63 win over The Citadel. He became the third NC State player to ever achieve the feat, joining Dennis Smith Jr. and Julius Hodge. He was named ACC player of the week on December 23. Johnson scored a career-high 28 points and made a halfcourt shot in a 88–66 upset of sixth-ranked Duke on February 19, 2020. At the conclusion of the regular season, Johnson was selected to the Second Team All-ACC. As a senior, Johnson led the ACC in assists per game while also averaging 12.8 points, 4.4 assists and 1.9 steals per game.
