Barrett also played for the Regional Elite Development Academy (REDA) under-12 program on the Amateur Athletic Union (AAU) circuit, facing many teams from the United States.

[9] Through grades seven and eight, Barrett attended École Secondaire Jeunes Sans Frontières, a French language school in Brampton.

[12] After his 27-point effort for St. Marcellinus against Bill Crothers Secondary School on October 9, 2014, Canadian recruiting website North Pole Hoops labeled him "special" despite only being in his first year.

[11] In February 2015, he was named MVP of the Guy Vetrie Memorial tournament after scoring 41 points and a making the game-winner for REDA in a 74–72 win over BTB Academy.

[16][17] In September 2015, one week after touring top prep schools in the United States, Barrett announced that he would leave St.

[21] Barrett erupted for 31 points on December 21, in a loss to Chino Hills High School at the City of Palms Classic quarterfinal.

[23] At the end of the season, after leading Montverde Academy in scoring, Barrett was named to the MaxPreps Freshman All-American First Team.

Entering 2016–17, Barrett's sophomore season for Montverde, he was among 20 players named to the USA Today High School Sports All-USA Preseason Team.

[26] In December, Barrett led Montverde to a City of Palms Classic title, scoring a team-best 15 points in the finals against Memphis East High School, and received tournament MVP honors.

[28] In February, Barrett garnered MVP accolades at Basketball Without Borders, a three-day camp during NBA All-Star Weekend.

[30][31] Barrett finished the season averaging 22 points and 7 rebounds per game in high school, being tabbed National Sophomore of the Year by MaxPreps and making the Naismith All-American Third Team.

[37] Barrett posted 22 points and 10 rebounds on January 15 to defeat Mater Dei High School at the Spalding Hoophall Classic.

[46][47] He received scholarship offers from several major universities including Arizona, Duke, Indiana, Kansas, Kentucky, Missouri, Oklahoma, Oregon, Texas, UCLA, and USC, according to ESPN.

"[51] Sources: On November 6, in his first regular season game, he posted 33 points and six assists against second-ranked Kentucky at the Champions Classic, breaking the Duke freshman scoring record in a debut.

[65] Following Duke's loss in the 2019 NCAA men's basketball tournament, Barrett announced his intention to forgo his final three seasons of collegiate eligibility and declare for the 2019 NBA draft.

[68] 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.

[88][89] 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.

[90] 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.

[91] It was reported by Zach Lowe of ESPN that some NBA insiders had labelled Barrett's contract "a toxic asset" following the trade.

[94] 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.

[95][96] Barrett was the youngest player on Canada's under-16 national team that won silver at the 2015 FIBA Americas U16 Championship, in Argentina.

[98][99] In July 2017, Barrett made headlines with a 38-point, 13-rebound, and five-assist showing as he guided Canada's under-19 squad to a 99–87 semifinal win over the US at the FIBA Under-19 Basketball World Cup.

[106] On September 3, they qualified to the quarter-finals of 2023 FIBA Basketball World Cup, in the process securing a berth at the 2024 Summer Olympics.

"[107] Barrett ultimately sealed the victory with a 3 point shot and won the bronze medal over the United States in the third-place game.

[112][113] Rowan Sr. was a long-time member of the Canadian national team, which he captained at the 2000 Summer Olympics, and later became executive vice president and general manager of Canada Basketball.

[113][114] Barrett is the godson of Steve Nash, a Basketball Hall of Fame inductee and former head coach of the Brooklyn Nets who played with his father on the Canadian national team.

[4] She was a nationally ranked sprinter and long jumper for St. John's University before working for the Canadian Imperial Bank of Commerce.

[2] His maternal aunt Dahlia Duhaney was a member of the Jamaica team 4 × 100 m relay that won a gold medal at the 1991 IAAF World Championships.

[117] Also on his mother's side, his grandparents ran track for the Jamaica national team, and his uncle played football for the University of Maryland.

[118] After Barrett graduated from high school, his brother Nathan joined the prep basketball team at Montverde Academy.