Johnson, a 6'5 shooting guard from Palma High School in Salinas, California, first played collegiately at Loyola Marymount.

[1] After sitting out the 2008–09 season per NCAA transfer rules, Johnson made an instant impact in the Big West Conference for the Gauchos, averaging 18 points and 5.9 rebounds per game.

Johnson also led the Gauchos to the 2010 Big West Conference men's basketball tournament title and an NCAA appearance.

Following the season, he was named the Big West conference player of the year and an honorable mention All-American by the Associated Press.

[23] He made his debut for the Suns the following day, recording seven points, one rebound and one steal in 19 minutes of action against the Utah Jazz.

Five days later, Johnson returned to the Austin Spurs, recording 17 points, eight rebounds, six assists and three steals in 43 minutes that night against the Oklahoma City Blue in a 96–94 win.

[26] On March 9, 2016, Johnson signed a 10-day contract with the New Orleans Pelicans to help the team deal with numerous injuries.

[27] That night, he made his debut for the Pelicans in a 122–113 loss to the Charlotte Hornets, recording five points and three rebounds in 20 minutes as a starter.

He helped the team reach the quarter-final round of the league but fell short of advancing to the semi-final stage after losing to Henan Roaring Elephants.

[33] On March 2, 2017, Johnson was acquired by the Austin Spurs of the NBA Development League, returning to the franchise for a third stint.

[38][39] On January 4, Johnson made his debut for the Pauian and scored 28 points with five rebounds, five assists, a steal and a block in an 87–73 win over the Yulon Luxgen Dinos.

[46] Following his junior season at UCSB, Johnson was chosen to represent the United States as a member of Team USA at the 2011 World University Games in Shenzhen, China.