New York Knicks (2019–2023) 2019–20 season On June 20, 2019, the
New York Knicks drafted Barrett with the third overall pick in the
2019 NBA draft. By then Barrett had been nicknamed "Maple Mamba" due to his playstyle resemblance to
Kobe Bryant. On July 3, Barrett officially signed with the Knicks. On October 23, 2019, Barrett made his debut in the NBA, starting in a 111–120 loss to the
San Antonio Spurs with 21 points, five rebounds, two assists and two steals. On December 17, Barrett scored a then career-high 27 points with six rebounds, an assist and a steal in a 143–120 win over the
Atlanta Hawks. Barrett came down with a sprained ankle in a game against the
Phoenix Suns on January 16, 2020. On March 2, Barrett tied his career-high 27 points by hitting a clutch layup before the game ended. He also had five rebounds, five assists and one steal in the 125–123 victory over the
Houston Rockets. Barrett finished his rookie season averaging 14.3 points, 5.0 rebounds, 2.6 assists, and 1.0 steals in 30.4 minutes. He appeared in 56 games, starting in 55. He was controversially left out of an
NBA All-Rookie Team after the premature end of the regular season.
2020–21 season On December 21, 2020, the Knicks announced that they exercised their third-year option on Barrett. On January 21, Barrett scored a then career-high 28 points, along with five assists and two rebounds, in a 119–104 win over the
Golden State Warriors. On March 13, Barrett scored a then career-high 32 points, along with five rebounds and three assists, in a 119–97 win over the
Oklahoma City Thunder. Barrett made significant strides in his second year, finishing with 17.6 points per game, 5.8 rebounds, and 3.0 assists. Barrett also made big improvements in his shooting, finishing the season shooting 40.1 percent from the three-point line, and 74.6 percent from the free throw line. Barrett started in all 72 games during the season, which was shortened due to the
COVID-19 pandemic, playing 34.9 minutes per game. The Knicks made the playoffs for the first time in eight years securing home court advantage in the first round. The Knicks ultimately lost 4–1 in the first round to the
Atlanta Hawks.
2021–22 season On January 6, 2022, Barrett recorded 13 points and six assists and ended the night with a contested game-winning three-pointer at the buzzer, giving the Knicks a 108–105 victory over the
Boston Celtics, on a night where New York trailed by as much as 25. On January 10, against the
San Antonio Spurs he scored 31 points, and on January 12 against the
Dallas Mavericks. Barrett scored 32 points setting a franchise record becoming the youngest Knick to get consecutive games with at least 30 points at just 21 years old. He also became the eighth NBA player to tally 2,000 points, 500 rebounds and 300 assists by 21 years old, joining Kevin Garnett, Kobe Bryant, Tracy McGrady, LeBron James, Carmelo Anthony,
Kevin Durant and Luka Doncic. On February 6, he scored a then career-high 36 points, along with eight rebounds and five assists, in a 122–115 overtime loss against the
Los Angeles Lakers. On February 25, Barrett scored a career-high 46 points in a 115–100 loss to the
Miami Heat. He became the 7th player in NBA history to score 3400+ points, 1100+ rebounds and 550+ assist's before turning 22 years old joining Kevin Garnett, Tracy McGrady, Carmelo Anthony, LeBron James, Kevin Durant, and Luka Doncic. He also became the youngest Knicks player to average 20 points per game for a season at 21 years old.
2022–23 season On September 1, 2022, Barrett re-signed with the Knicks on a four-year, $120M deal. He was the first player to agree to a multiyear extension after a rookie deal with the Knicks since
Charlie Ward in 1999.
Toronto Raptors (2023–present) On December 30, 2023, the Knicks traded Barrett, along with
Immanuel Quickley and a 2024 second-round draft pick, to the
Toronto Raptors in exchange for
OG Anunoby,
Precious Achiuwa and
Malachi Flynn. In his first game with his hometown Raptors on January 1, 2024, Barrett put up 19 points and nine rebounds on 50 percent shooting from the field goal in a 124–121 win against the
Cleveland Cavaliers. It was reported by
Zach Lowe of ESPN that some NBA insiders had labelled Barrett's contract "a toxic asset" following the trade. On January 7, 2024, Barrett scored a season-high 37 points on 13 of 20 shooting, along with 6 rebounds and 6 assists in a 133–118 win over the
Golden State Warriors. On November 1, 2024, Barrett recorded a season-high 33 points and achieved a then career-high 12 assists in a 131–125 loss against the
Los Angeles Lakers. On November 16, Barrett achieved his first career triple-double with 25 points, 10 rebounds, and a career-high 15 assists in a 126–123 overtime loss to the
Boston Celtics. On May 1, 2026, with 1.2 seconds left in overtime of Game 6 of the first round of the NBA Playoffs against the
Cleveland Cavaliers and the Raptors down a point facing imminent elimination, Barrett hit a rim-bounce game-winning three pointer to win the game and force a deciding game seven. ==National team career==