Johnson played college basketball for four different colleges including Cisco Junior College in Texas and Los Angeles Southwest Junior College, where he averaged 22.3 points, 12.2 rebounds and 2.4 blocks per game as a sophomore. He then transferred to the University of Oregon on a scholarship.
Johnson began his professional career in the NBA D-League where he played for the Anaheim Arsenal and Rio Grande Valley Vipers from 2007-2008. After that, he played in the Korean Basketball League with the Changwon LG Sakers and Jeonju KCC Egis from 2008-2010. He was "banned forever" from the KBL for directing the middle-finger gesture at a referee during the final game of the championship series. After the game, the KBL held a meeting and also decided to fine Johnson US$4,448.
On December 9, 2011, Johnson signed with the Atlanta Hawks. On April 13, 2012, Johnson was sent home and fined an undisclosed amount of money for "conduct detrimental to the team." Just three days later on April 16, 2012, Johnson scored a career high 21 points against the Toronto Raptors. On May 12, 2012, the NBA fined Johnson $25,000 for gesturing, again with his middle finger, at a Boston Celtics fan following the Hawks’ elimination from the playoffs. On September 18, 2012, Johnson signed a one-year deal to return to the Atlanta Hawks.
On January 13, 2016, Johnson signed once again with the defending champion Tropang TNT as the team's import for the 2016 PBA Commissioner's Cup. Days before the Commissioner's Cup, he was figured in a brawl with two players of Blackwater Elite in the team's tune-up game in Moro Lorenzo Gym. Johnson was suspended for one game and fined 50,000 pesos after the incident. On February 13, 2016, Johnson was "banned for life" from the PBA and fined 250,000 pesos after he disrespected and cursed the PBA commissioner Chito Narvasa during their game against Meralco Bolts, earlier in the game he was called for a technical foul for second motion on Meralco's Forward/CenterKelly Nabong and a flagrant foul one penalty after he gave an elbow to the face of Meralco's Forward/Center Bryan Faundo and his second technical foul came from his encounter with the commissioner Narvasa that led him to be ejected from the game. Johnson, through his Twitter account, later apologized to Commissioner Narvasa and thanked the PBA for giving him the chance to return as the import of the Tropang TNT for the second consecutive time. In a press conference, Narvasa accepted Johnson's apology, three days after the incident. The PBA later downgraded the ban order to a suspension good for one season and the fine has been reduced to 150,000 pesos.
On March 9, 2016, Johnson signed with Petrochimi Bandar Imam of the Iranian Super League. However, he never played for the Iranian team. On April 25, he left Petrochimi and signed with Caciques de Humacao for a second stint.
After a stint in the BIG3, Johnson returned to professional, 5-on-5 basketball after being signed by the Alab Pilipinas of the ASEAN Basketball League as its new World Import. This will be Johnson's third stint playing in the Philippines.
