He previously played for the Illawarra Hawks of the Australian National Basketball League (NBL).

[1] Johnson for his senior year decided to attend Donda Academy, Kanye West's school in Simi Valley, California.

[6] On April 13, 2023, Johnson announced his decommitment from Texas and announced his plan sign with the Illawarra Hawks of the National Basketball League in Australia, joining LaMelo Ball, who went from a 2nd round pick to potential 1st pick with NBL's Next Stars program, as the second player to join the team out of high school.

[5] Sources: On April 13, 2023, Johnson signed a contract with the Illawarra Hawks of the National Basketball League in Australia joining the NBL's Next Stars program.

[10] Johnson made his NBA debut on October 23, 2024, in a 124–109 win over the Philadelphia 76ers[11] and throughout his rookie season, he has been assigned several times to the Wisconsin Herd.