Johnson began and spent the majority of the 2019-20 season with the Phoenix Suns. The 6-foot-3 combo guard appeared in 31 games (three starts) for the Suns and averaged 5.7 points, 1.7 rebounds and 1.6 assists in 16.6 minutes per game. Arguably his best performance as a Sun occurred Nov. 2 during a win at Memphis. In that contest, Johnson recorded nine points (3-4 FG, 3-3 3Pt), five assists and no turnovers in 20 minutes. He was waived by the Suns on Feb. 10, but eventually picked up by the Nets on June 24, ahead of the NBA's restart in the Orlando bubble. Johnson saw a significant boost in playing time for the short-handed Nets. In Orlando, he averaged 12.0 points, 3.0 assists and 3.0 rebounds across 24.3 minutes per game while playing in all eight seeding contests, with four starts. His best performance in the bubble was during a nine-point win over the Clippers on Aug. 9, when Johnson recorded a season-high 21 points (6-11 FG, 5-9 3Pt, 4-4 FT), three rebounds and one assist in 30 minutes. In the first round of the playoffs against the Raptors, Johnson averaged 13.8 points, 2.3 assists and 1.8 rebounds in 23.2 minutes and started two of Brooklyn's four games. The Fresno State product produced 38.9 percent shooting from behind the arc with Brooklyn, which would have been a career high had he achieved the feat across the entire season.

Johnson split time between Miami and Phoenix in 2018-19, appearing in 44 contests with the Heat before being traded to the Suns on Feb. 6. Johnson then appeared in 13 contests with Phoenix before a knee injury ended his campaign prematurely. He didn't appear in any games after March 13. On the year, the 26-year-old averaged 10.9 points per game to go along with 3.0 rebounds and 2.9 assists. He scored in double figures 31 times, including a season-high 29-point performance on Feb. 23 (vs. Atlanta). Per 100 possessions, Johnson's 8.3 three-point attempts per game represented a career high and is indicative of his confidence and growth as a shooter. He finished the season shooting 34.6 percent from beyond the arc. His shooting stroke peaked in December, as Johnson converted on 50 percent of his threes taken over his 12 games that month. The trade to Phoenix had a positive effect on Johnson's playing time, as he averaged close to six more minutes per night with the Suns than he did as a member of the Heat. He saw 12 starts in those final 13 games with Phoenix, when he put up 11.1 points, 4.2 assists, 4.0 rebounds and 1.1 steals across 31.5 minutes. The knee surgery that ended his year early was merely a clean-up procedure, and it shouldn't affect his outlook heading into his age-27 season.

The Fresno State product once again proved to be an effective weapon for the Heat no matter his role. Johnson started 39 games during the 2017-18 season and came off the bench in 33 others, but he played well in both instances. Johnson played north of 24 minutes (28.5) for a third consecutive year, while averaging doubles figures in scoring (11.7) for a second straight season. Johnson's strongest stretch of the season was a 15-game run from late November to late December in which he averaged 15.7 points. His 31-point effort in a win over the Magic on December 30 was a season-high mark for him. Johnson is a solid three-point shooter and has gotten progressively better from deep in each of his four NBA seasons. His 1.7 threes per game in 2017-18 were a career best and, to make things even better, he shot 36.7 from downtown over the course of the season, making a career-high five three-pointers on two separate occasions. Johnson also scored in 82.2 percent of his free-throw attempts and that marked the third straight season in which Johnson drilled at least 75 percent of his free throws.

Johnson received a qualifying offer from the Nets in the offseason, but it was matched by the Heat, setting the stage for a third year in Miami. He worked as a starter periodically in the preseason but ultimately came off the bench by the Oct. 26 season opener. Johnson scored 15 points in that contest, starting a streak of seven consecutive games in double figures, over which he averaged 14.4 points and 4.6 rebounds. It was a season of career bests for Johnson, who set a new mark with 27 points in a Dec. 7 matchup against Atlanta. Later in the month, he topped that mark against Orlando with 32 points while also chipping in five rebounds, three assists and three steals. Shoulder troubles resurfaced again in January and cost Johnson five games, but he was able to pick up right where he left off. Over the final 33 games of the regular season, Johnson put up 13.2 points, 3.6 rebounds and 3.2 assists over 28.4 minutes. He surprisingly didn't start a single game in his third NBA season, but Johnson still finished with career highs in scoring (13.7 ppg), rebounding (4.0 rpg) and games played (73). He was the fourth highest-scoring player on a 41-41 team that narrowly missed the postseason.

Johnson suffered a broken jaw during the Summer League before his second NBA season, but he recovered on time to join the Heat in camp. He saw less than two minutes over the first two games of the regular season while recovering from a back/tailbone injury, but he then started to see his workload ramp up. Johnson averaged 10.1 points across 22.8 minutes over the next 18 games, establishing his role as a key reserve. That momentum halted just a bit when he suffered a shoulder sprain in practice and proceeded to miss eight of the next nine games. Johnson returned to action Dec. 28 and ended up drawing five starts in the next 16 games, averaging 8.3 points and 4.0 rebounds over that span. He even saw a season-high 39 minutes Jan. 17 against the Thunder. After that, his shoulder troubles resurfaced, and Johnson was forced to undergo a surgery that sidelined him for two months. He didn't see action again until the Game 7 of the Eastern Conference Playoffs opening round, tallying five points and two assists in six minutes. The Heat won that series and advanced to play Toronto in the semifinal round, ultimately losing in seven games. Johnson missed the first three games of that series, but he averaged 4.0 points, 1.5 assists and 1.5 rebounds over the final four contests.

Johnson was not selected in the 2014 NBA Draft, but played Summer League ball with Miami and signed with them Aug. 7. The Fresno State product ultimately didn't make the final roster, but was picked up by the Heat's D-League affiliate, the Sioux Falls Skyforce. Over 15 games there, the 6-foot-4 guard averaged 18.5 points, 4.5 rebounds and 4.3 assists over 34.5 minutes. He was given a 10-day contract in January and made his debut Jan. 14 against the Warriors, logging two points in two minutes. That was the only action he saw under that contract, but he was offered another 10-day deal a week later and started to factor in the rotation. There was even a seven-game stretch in February over which he averaged 8.0 points and 2.9 rebounds over 19.6 minutes. He signed for the remainder of the season on Feb. 8, and less than a month later, scored a career-high 26 points in a March 3 victory over the Suns. Three games later, Johnson put up 24 points in a win over the Kings. He had his first career double-double over 48 minutes in the regular-season finale April 15, tallying 11 points, 10 rebounds, four assists and four steals in a win over the Sixers. The Heat finished 37-45 and missed the postseason, but Johnson laid the foundation for a bigger role in years to come.