Johnson attended Trinity Episcopal School in Richmond, Virginia and played college baseball at the University of South Carolina.
[1] Johnson spent his first professional season with the Great Falls Voyagers (where he earned Pioneer League All-Star honors)[2] and Kannapolis Intimidators, pitching to a 1–1 record and a 3.86 ERA with 37 strikeouts in 25+2⁄3 innings in 22 relief appearances between both teams.
[3] In 2018, he pitched with Kannapolis, with whom he was named a South Atlantic League All-Star, and the Winston-Salem Dash,[4][5] going 9–0 with 14 saves and a 1.40 ERA and a 0.88 WHIP over 58 relief innings in which he struck out 89 batters with both clubs.
After the season, he was selected to the United States national baseball team for the 2019 WBSC Premier 12,[8] but he did not pitch in the tournament.
[11] He made 16 appearances split between Kannapolis, Winston-Salem, and the Triple-A Charlotte Knights, but struggled to a 9.56 ERA with 22 strikeouts in 16 innings pitched.