In his second season for the Utah Jazz, Mitchell started 77 games. He set new career highs in terms of minutes per game (33.7), points per game (23.8), assists per game (4.2), and rebounds per game (4.1). On Jan. 25 Mitchell set a career high with 11 assists during a 106-102 win over the Minnesota Timberwolves. Twice during the 2018-2019 season Mitchell scored a career-high 46 points. On Mar. 2, he scored 46 points during a 115-111 victory over the Milwaukee Bucks. The next month on Apr. 9, he matched the feat as his team bested the Denver Nuggets 118-108. Mitchell finished the year with 1,829 total points, which led the Jazz and was the 11th most in the league. He also netted 188 three-point field goals, which was the 16th highest total in the NBA. He was twice named NBA Player of the Week. His first honor came on Jan. 14 and his second award came on Mar. 4. Mitchell's Jazz ended the season with a 50-32 record and lost to the Rockets in the first round of the playoffs. The high-scoring guard has two seasons remaining on his rookie contract with the Jazz.

The 13th overall pick in the 2017 NBA Draft made his professional debut with a 10-point, four-assist night in a 106-96 win against Denver. He played in 79 games, making 71 starts and scoring 20.5 points, 3.7 rebounds, 3.7 assists, and 1.5 steals per game while playing 33.4 minutes a night. He scored a season-high 41 points against New Orleans on Dec. 1. The Louisville product would score 40 points while adding six assists and five rebounds against Phoenix on Feb. 2. Mitchell recorded seven games with at least 30 points, including a pair of 35-point outings against Charlotte on January 12 and San Antonio on March 23. He played in 11 playoff games, scoring a playoff high 38 points in a decisive Game 6 win in the Western Conference Quarterfinals against the Oklahoma City Thunder on April 27. Mitchell then recorded his first career double-double in Game 1 of that series with a 27-point, 10-rebound effort against the Rockets. He'd go on to post two more double-doubles, a 22-point, 11-assist effort in Game 3 of the First Round and a 17-point, 11-assist tally in Game 2 of the Conference Semifinals against Houston. Mitchell was ultimately named Rookie of the Month four times in December, January, February and March. He was also named to the NBA All-Rookie First Team and finished second in Rookie of the Year voting.