Bay Area Schuckers (2011) Johnson played for the Schuckers at the
APBL, a semi-professional men's minor basketball league where he showed his versatility as a player and averaged 17.5 points, 9 rebounds and 4 assists.
Moving to and settling in Indonesia (2012–14) In 2012, despite not having a team to play for and working full-time as a salesman, Johnson continued to work on his game. Eventually in 2012, he got the opportunity to come to Indonesia to teach the children of Indonesia on how to play basketball. Together with his team from
Athletes in Action, Johnson flew over and began coaching there. He also had the opportunity to coach for the prestigious
Pelita Harapan University men's basketball team.
CLS Knights Surabaya (2014–17) In 2014, Johnson met with the owner of
CLS Knights Surabaya whilst playing basketball, whom invited him to join his team and play in the
IBL, the professional league in Indonesia. As the league then still prohibited the use of foreign players, Johnson decided to become a naturalized citizen of Indonesia. After going through one year long process of converting his citizenship, he was finally granted Indonesia's citizenship.
MVP and Championship Season (2015–16) Johnson made an immediate impact during the pre-season and finishing the pre-season with an average of 15.67 points, 13.3 rebounds and 4 assists to go with his 2 steals and 1.3 blocks average. Johnson and CLS were eliminated in the semi-final of the preseason in an overtime lost to
Aspac Jakarta despite a 37 points, 13 rebounds and 9 assist performance from him. Despite losing in the pre-season, CLS Knight was still viewed as the favorite to win the 2016 championship. Jamarr made his official debut in Indonesia, on January 10, 2016. Johnson dominated the league and ended the season with a league-leading record of 31 wins and only 2 defeats. He also led the league in points with an average of 15.25 points per game and won the MVP and Rookie of the Year award. Johnson helped CLS to win the regular season IBL title, by defeating
Pelita Jaya in 3 games and winning the Finals MVP award.
Departure from Indonesia (2016–17) There was a major rule change during his second season at the IBL. At the 2016-17 off-season, IBL announced that the league will now allow each team to draft 2 foreign players. Despite Johnson's Indonesian citizenship, he was still considered a foreign player and thus immediately took up one of the foreign player space for CLS Knights. In exchange, CLS was granted the first overall pick for the
2016 IBL Foreign Draft and used it to pick
DeChriston McKinney. However, during the mid-season of 2017 Johnson was cut from the team and was replaced by
Duke Crews as he was performing below expectation. There were also reports that he clashed with CLS' star point guard,
Mario Wuysang and nearly gotten into an altercation during one of the practice. He ended the season averaging 11.5 points, 8.6 rebounds and 2.3 assists.
Dunkin Raptors (2017) Johnson signed with the Dunkin Raptors of the Thailand Basketball League. In his debut, he scored 12 points and grabbed 9 rebounds to help the Raptors win against OSK R.Airline.
Satria Muda Pertamina Jakarta (2018–19) Return to Indonesia and second championship (2017–18) In January 2018, Johnson signed with
SM Pertamina of the
Indonesian Basketball League, replacing
Kevin Bridgewaters as the other foreign player for the remainder of the
2017-18 IBL season. Due to his Indonesian citizenship, the height restriction for foreign player did not apply for Johnson and Satria Muda was allowed to have two big foreign import in their team to complement their talented guard lineup. He made his debut for SM with 8 points, 8 rebounds and 3 assists against
NSH Jakarta on January 4, 2018. He finished the season averaging 14 points, 8.8 rebounds, 3.8 assists, 1.3 steal and 1.2 block. This season, despite not having a noticeable difference in his stats, Jamarr actually changed his playing style from the more explosive, high-flying forward to a more team-oriented, passing forward with an ability to shoot from the three point lines. He entered the
2018 IBL Playoffs as the first seed in the Red Division and faced
Hangtuah Sumsel in the divisional final. After beating Hangtuah in 3 games, Johnson and Satria Muda met Pelita Jaya in the final; which so happen to be the team that defeated Satria Muda in the previous year's final, albeit without having Johnson in the team. This year however, Satria Muda came out victorious after defeating Pelita Jaya in 3 games and Johnson won the Finals MVP award.
First all-star with Satria Muda & Torn Achilles Injury (2018–19) Johnson returned to Satria Muda for the 2018–19 season together with
Dior Lowhorn. On January 5, 2019, he was selected as an all-star starter for the red division. He finished the season as the third seed with 9 wins and 9 losses while averaging a career-high in points and rebounds. On 2 February 2019, Johnson suffered an Achilles injury during Game 01 of the Red Division's semifinal against
NSH Jakarta. He underwent surgery the very next day and was ruled out for the rest of the playoff.
Louvre Surabaya (2019–23) In mid-November,
Louvre Surabaya announced that they will be adding Jamarr to their official roster, however Jamarr will not be available for the upcoming 2020 IBL season while still recovering from injury. It was clarified by the owner that Jamarr, along with Brandon Jawato whom also happen to be a naturalized player will not participate in the 2020 season and their addition to the team is for the long-term plan of the team beyond 2020.
Borneo Hornbills (2023–present) In 4 December 2023, Johnson comes back to the
Indonesian Basketball League, playing for the Borneo Hornbills who recently changed their name from Bumi Borneo Pontianak. == International career ==