Stall High School to the South Carolina AAA football championship, Johnson received a basketball scholarship at the College of Charleston, where his older brother Steven was a standout years earlier.

He was the first player in College of Charleston history selected in the NBA Draft, picked by the Sacramento Kings in the late second round.

He drew a five-game suspension from the NBA as a result of his actions in the Pacers–Pistons brawl which broke out at The Palace of Auburn Hills near the end of a November 19, 2004 game between the two teams.

In the 2006 off-season, Johnson was traded to the Dallas Mavericks in exchange for guard Darrell Armstrong, and forwards Josh Powell and Rawle Marshall.

[2] On February 16, 2008, the Sacramento Kings acquired Johnson along with Shelden Williams, Tyronn Lue, and Lorenzen Wright in exchange for Mike Bibby.