After going unclaimed in the 2019 NBA Draft, Brissett signed with his hometown Raptors. He came off the bench for 19 appearances with the big club, adding another 28 games (21 starts) for the Raptors 905 in the G League. Brissett averaged 15.8 points, 6.9 rebounds and 1.0 steals for the 905. Working around ankle and knee injuries, he played 7.1 minutes per game for the Raptors, averaging 1.9 points and 1.4 rebounds. He also shot a noteworthy 80 percent from the free-throw line. In his best game of the year, Jan. 7 versus Portland, the rookie popped for 12 points on 5-of-9 shooting (including a pair of threes) along with six rebounds, an assist and a steal.