[7] In his first game of Big East play, Johnson scored 20 points and grabbed a career high 19 rebounds as Syracuse defeated Seton Hall 80–73 on December 29, 2009.

[8] Johnson was named Big East Player of the Year on March 9, 2010, finishing with season averages of 16.0 points and 8.4 rebounds.

Johnson would not gain significant playing time with the Suns until Lindsey Hunter took over as head coach for the team.

On February 26, 2013, Johnson recorded 14 points, along with 9 rebounds, 3 assists, and 2 steals in an 84–83 victory against his former team, the Minnesota Timberwolves.

A day later, Johnson made a game-tying three-pointer from a long pass by Jermaine O'Neal that helped the Suns win 105–101 in overtime against the San Antonio Spurs.

On March 1, 2013, Johnson scored a season high 15 points and added six rebounds and two steals in a 92–87 victory against the Atlanta Hawks.

[19] He made his debut for the Clippers in the team's season opener against the Sacramento Kings on October 28, recording 3 points and 1 steal in a 111–104 win.

[22] On February 7, 2019, Johnson was traded to the Washington Wizards in exchange for Markieff Morris and a 2023 second-round pick.

[25] In his first career game with Panathinaikos, Johnson scored 7 points in 19 minutes of playing time against AEK Athens.