Mitchell opened the 2019–20 season with a 32-point, 12-assist performance in a 105–95 win over the Oklahoma City Thunder on October 23, 2019. On November 3, Mitchell scored a then season-high 36 points in a 105–94 loss to the Los Angeles Clippers. On November 23, he surpassed that season-high with 37 points in a 128–120 victory over the New Orleans Pelicans. On December 28, Mitchell recorded 30 points, seven rebounds and nine assists in a 120–107 win over the Clippers. On January 16, 2020, Mitchell tied his career-high 46 points in a 138–132 overtime loss to the Pelicans. On January 30, Mitchell was named an All-Star for the first time in his career, being selected as a Western Conference reserve for the 2019 NBA All-Star Game. On February 24, Mitchell scored 38 points in a 131–111 loss to the Phoenix Suns, before scoring 37 points two days later, in a 114–103 loss to the Boston Celtics.