Johnson grew up in Louisville, Kentucky, and attended Trinity High School. As a sophomore, Johnson averaged 10.5 points and 4.8 rebounds per game and was named third team All-State.[1] He was named first team All-State as a junior after averaging 13.9 points, 5.8 rebounds and 5.2 assists per game.[2][3] Johnson was ranked a four-star recruit and the best college prospect in the state of Kentucky by ESPN and committed to play at Louisville early during his senior year.[4][5] He de-committed after Louisville was named as part of the 2017–18 NCAA Division I men's basketball corruption scandal, but recommitted after considering offers from Georgia and Xavier.[6] As a senior, Johnson averaged 16.1 points, 7.2 rebounds and four assists per game and was named First Team All-State and the Player of the Year by the Lexington Herald-Leader. He was named the MVP of the Kentucky Sweet 16 state tournament after recording 22 points, 12 rebounds, two assists and four blocked shots in the state title game.[7] He scored 1,472 points and grabbed 719 rebounds in four seasons as a starter at Trinity.[8]
College career
Johnson missed the beginning of his freshman season with an offseason shoulder injury.[7][9] Johnson played mostly as a key reserve during his freshman season with occasional starts. He scored a season high 19 points with seven assists, four rebounds and three steals in Louisville's upset win over Duke on January 18, 2020.[10] Johnson started at point guard against Syracuse on February 19, 2020, and led the team with seven assists in the 90–66 win in addition to three points.[11] Johnson averaged 6.3 points, 2.8 assists and 2.8 rebounds per game in 27 games with four starts for the season.[12] As a sophomore, he averaged 12.6 points, 3.2 assists and 5.8 rebounds per game. Following the season, he declared for the 2021 NBA draft.[13] Johnson was a projected lottery pick in the middle of the year for the 2021 NBA draft[14]
On October 15, 2022, Johnson signed an Exhibit 10 contract with the Toronto Raptors and was waived later that day.[17] He then joined the Raptors 905 as an affiliate player.[18]