The 2019-20 season marked Ferguson's third in the league and third with the Thunder. The 21-year-old averaged 3.9 points, 1.3 rebounds, 0.9 assists, 0.5 steals and 0.3 blocks in 22.4 minutes per game. Ferguson appeared in 58 out of a possible 72 games during the pandemic-shortened season, with 38 starts. During a 127-119 win over the 76ers Nov. 15, Ferguson recorded a season-high 19 points in addition to two assists, two rebounds and one steal in 39 minutes. Three days later against the Clippers, Ferguson recorded a career-high seven rebounds in 35 minutes, also contributing five points and two steals. Later in the month, Nov. 25 in a win over Golden State, Ferguson blocked a season-high two shots. He would reach that mark again later Jan. 9 in a win over Houston. On Jan. 15 against the Raptors, the 6-foot-6 wing swiped a season-high three steals in addition to two points, one assist and one block in 21 minutes. Ferguson recorded a season-high five assists in 24 minutes during the NBA bubble against the Heat on Aug. 12, also posting three points, one steal and one block. Ferguson appeared in four of a possible seven playoff games against the Rockets. In those contests, he totaled six points, four rebounds, one assist and one steal in 42 minutes.

After playing a very small role for the Oklahoma City Thunder as a rookie during the 2017-18 season, Terrance Ferguson took a big step forward in his sophomore campaign. Throughout the season he had stretches in which he looked like an impactful NBA starter. It was a promising development as the 6-foot-7 Oklahoma native started all 74 games in which he appeared. Ferguson averaged 6.9 points and 1.9 rebounds on 42.9 percent shooting. He was especially impressive during the month of January. In 13 games that month, the ultra-athletic guard averaged 10.8 points on 49.5 percent shooting and converted 47.9 percent of his three-pointers. After attempting 5.8 shots per game in the regular season, that number dropped to an even 5.0 in the playoffs. During Oklahoma City's first-round playoff series, Ferguson averaged 25.6 minutes per contest. He posted per-game averages of 5.0 points and 2.4 rebounds in the five-game battle. He also shot 38.9 percent from deep, averaging 1.4 three-pointers per contest.

Ferguson took an unusual route to the NBA, skipping college to play professionally in Australia for the Adelaide 36ers. The shooting guard was then selected with the 21st pick of the 2017 NBA Draft by Oklahoma City. He appeared in 61 games during his rookie season, starting 12 of them. Ferguson averaged 3.1 points, 0.8 rebounds and 0.3 assists over 12.5 minutes of run. He debuted on Oct. 19, scoring two points in 10 minutes against the Knicks. The guard was also assigned to the Oklahoma City Blue of the NBA G League in November. He played three games for the Blue, averaging 14.7 points and 1.3 steals. Ferguson started for the first time on Jan. 3 against the Lakers, scoring a career-high 24 points (9-for-12 FG) in 32 minutes. He scored in double digits five times in the season. The Thunder finished with a 48-34 record but lost to the Jazz in the first round of the playoffs. Ferguson appeared in three games, totaling three points, one rebound and one assist in just over six minutes.