Oklahoma City Blue (2015–2017) On June 25, 2015, Johnson was selected by the
Oklahoma City Thunder with the 48th overall pick in the
2015 NBA draft. He later joined the Thunder for the
2015 NBA Summer League where he averaged 7.6 points and 8.6 rebounds in five games. On November 3, 2015, he was acquired by the
Oklahoma City Blue of the
NBA Development League, the affiliate team of the Thunder. On November 14, he made his professional debut in a 110–104 loss to the
Austin Spurs, recording 16 points, nine rebounds, one assist, one steal and one block in 33 minutes. Johnson appeared in all 50 games for the Blue in 2015–16, averaging 12.3 points, 8.1 rebounds, 2.0 assists and 1.6 blocks per game. He subsequently earned NBA D-League All-Rookie Team honors. Johnson returned to the Blue for the 2016–17 season, and on February 6, 2017, he was named in the Western Conference All-Star team for the 2017 NBA D-League All-Star Game.
Oklahoma City Thunder (2017–2018) . On July 22, 2017, Johnson signed with the
Oklahoma City Thunder. He scored four points in his NBA debut on October 19, 2017, in the Thunder's 105–84 win over the
New York Knicks. During his only season with the
Oklahoma City Thunder, he started six games for the team where he replaced
Steven Adams. As the starting center for the team they went 5–1 in those games. Johnson was a plus-26 in point differential in those six games, including a plus-26 in rout to a victory against the
Los Angeles Clippers when Johnson held his own against
DeAndre Jordan. Johnson's averages for those six games were 15 minutes, 5.2 points, 2.2 rebounds, 0.3 turnovers, 64.7 percent shooting and 60 percent foul shooting. On July 20, 2018, Johnson was traded to the
Orlando Magic in exchange for
Rodney Purvis. Cash considerations were also sent to the Magic. On July 23, 2018, Johnson and the draft rights to
Tyler Harvey were traded to the
Memphis Grizzlies in exchange for
Jarell Martin and cash considerations. On August 31, 2018, Johnson was waived by the
Memphis Grizzlies.
Qingdao Eagles (2018–2019) On September 11, 2018, Johnson was reported to have signed with
Qingdao DoubleStar Eagles of the
Chinese Basketball Association (CBA).
Anuyi Wenyi (2019) On August 23, 2019, Johnson was reported to have played for
Anhui Wenyi of the
National Basketball League (NBL) and returned with a championship and
most valuable player honors.
Return to the Eagles (2019–2022) In the 2019–20 season, Johnson averaged 23.7 points, 14.5 rebounds, 3.0 assists and 1.6 blocks per game. On September 9, 2020, Johnson re-signed with Qingdao. == NBA career statistics ==