Georgetown (2004–2007) Johnson was then brought on as an assistant to the newly appointed head coach at
Georgetown, John Thompson III, in 2004. The team was coming off of a losing record and made it to a
2005 National Invitation Tournament. During his tenure at Georgetown, he helped coach the team to an overall 72–30 record over 3 seasons and the
2006–07 team the
2007 Big East regular season championship, the
2007 Big East men's basketball tournament championship, and a trip to the
Final Four of the
2007 NCAA Division I men's basketball tournament.
Princeton (2007–2011) When Scott abandoned his struggling Princeton team to coach at Denver in 2007,
athletic director Gary Walters hired Johnson to take over the program. Johnson emerged from a field of
Princeton offense veterans that included Mike Brennan, Robert Burke,
Craig Robinson,
Bill Carmody,
Armond Hill,
Chris Mooney, and
Mitch Henderson. Johnson's demeanor as a coach was said by players to be more benevolent than his predecessor,
Joe Scott, who left for the
University of Denver after compiling a losing record in three years at Princeton. Among the lowlights that the team had achieved during the Scott era was a 21-point performance that tied the record for fewest points since the inception of the three-point shot and the
shot clock. The team had ranked last in the nation in scoring in both 2006 and 2007. Johnson employs the Princeton offense. Former Tiger stars
Brian Earl and
Scott Greenman were among Johnson's assistants at Princeton. After a tumultuous first season of rebuilding during which it posted a 3–11 record, Princeton began to show great improvement in 2008–2009. Even with only three games left on their schedule and a 7–4 conference record, they still controlled their own destiny for a possible postseason bid. The Ivy League does not name a coach of the year in any sport, but
Collegeinsider.com named Johnson Ivy League Coach of the Year. During Johnson's third season, the
2009–10 team rebounded from a 2–4 start to win 20 of its final 25 games and earn a berth in the
2010 College Basketball Invitational. Princeton's 22 wins were its most since 1999, as were its two postseason wins, and the postseason berth was its first since 2004. In the March 17, opening round game at home, Princeton defeated the
Duquesne Dukes 65–51. The game was Princeton's first postseason appearance since the
2003–04 team went to the
2004 NCAA Division I men's basketball tournament and the first postseason victory since the
1998–99 team won two games in the
1999 National Invitation Tournament. On March 22, the team defeated
IUPUI 74–68 in double
overtime at
IUPUI Gymnasium in
Indianapolis, Indiana. The Tigers had previously won in the postseason in Indianapolis when the Johnson-led 1995–96 team pulled off a first round upset of the national defending champion UCLA in the 1996 Tournament. In the tournament semifinals the team was defeated by
Saint Louis University 69–59 at
Chaifetz Arena in
St. Louis, Missouri on March 24. Johnson again earned Collegeinsider.com Coach of the Year. In 2010, Johnson tweaked the motion Princeton offense to be a bit more uptempo, resulting in more possessions and higher scores. On March 5, 2010, the
2010–11 team had a chance to clinch an outright
2010–11 Ivy League men's basketball season championship, but lost to
Harvard who clinched a share of the title. Following the game, Johnson made his team sit on the bench and watch the Harvard fans celebrate. On March 8, Princeton defeated Penn to force a one-game playoff at the
Payne Whitney Gymnasium in
New Haven, Connecticut. On March 12, Princeton earned the Ivy League's automatic bid to the
2011 NCAA Division I men's basketball tournament, making the
NCAA Division I men's basketball tournament for the first time since 2004 and 24th time in school history by defeating Harvard 63–62. Princeton was awarded the number thirteen seed and a first round match against the
Kentucky Wildcats. Kentucky had eliminated Ivy League representative
Cornell the prior season. Kentucky emerged victorious by a 59–57 margin on a last second layup. He was named as a finalist for the
Hugh Durham Award, the
Ben Jobe Award, and the
Skip Prosser Award.
Fairfield (2011–2019) In April 2011, Johnson accepted a head coaching position at Fairfield University, replacing
Ed Cooley. He coached the
2011–12 Stags to the semifinals of the
2012 CollegeInsider.com Postseason Tournament where they lost to
Mercer, after defeating
Yale,
Manhattan and
Robert Morris to finish with a 22–15 record. Mercer went on to win the tournament. For the second season in a row, he was a finalist for the Ben Jobe Award. The
2012–13 team started the season 10–10 (2–6) before winning five consecutive and seven out of eight
Metro Atlantic Athletic Conference games. The team then lost its two final conference games to finish 9–9 in conference. Eventually the team finished 19–15 (9–9). On March 11, 2019, Fairfield fired Johnson. He finished at Fairfield with an eight-year record of 116–147.
Air Force (2020–2021) Johnson was named associate head coach on former Princeton basketball player
Joe Scott's staff at
Air Force for the 2020–21 season.
USA Basketball Johnson served as a
USA Basketball scout for the February 2020 FIBA AmeriCup Qualifying Team. He later served as head coach of the July 2023 3x3 Men's U23 Nations League Team and the gold medal winning
2023 FIBA 3x3 U23 World Cup team. Then he served as an assistant coach for the
2025 AmeriCup Qualifying Team in February 2024.
Chicago Sky (2024) On February 26, 2024, Johnson was added to the staff of the
Chicago Sky as an assistant on
Teresa Weatherspoon's coaching staff.
Washington Mystics (2025–present) On December 23, 2024, Johnson was named head coach of the
Washington Mystics. ==Personal life==