As a senior, Brown helped lead his team to victory in the Georgia High School Association Class 6A State Championship.

[7] Brown won a 2014 FIBA Americas Championship gold medal as part of the USA Basketball Men's U18 National Team.

[11] On May 1, 2015, Brown committed to play for the Golden Bears at the University of California, Berkeley, under coach Cuonzo Martin and alongside fellow top-recruit Ivan Rabb.

[13] Sources: Brown took a masters-level class in Berkeley's Cultural Studies of Sport in Education program during his first semester in college.

[24] On July 27, he signed his rookie scale contract with the Celtics after averaging 16.0 points, 6.2 rebounds and 2.3 steals in six Summer League games.

[25] Brown made his debut for the Celtics on October 26, 2016, in the season-opening 122–117 victory over the Brooklyn Nets, scoring nine points on 3-for-4 shooting while also adding two blocks in 19-plus minutes.

[32] The duo made their debut in the Celtics' season-opening 102–99 loss to the Cleveland Cavaliers on October 17, 2017, where Brown scored a then-career-high 25 points.

He returned to action on May 3 in Game 2, scoring 13 points off the bench in a 108–103 victory, helping the Celtics take a 2–0 series lead.

[44] Brown struggled to start the season, with the Boston Globe criticizing him for taking too many two-point jump shots and an overall "lack of focus and discipline.

"[46] On December 6, 2018, Brown returned after missing three games with a bruised lower back and scored 21 points in a 128–100 victory over the New York Knicks.

[52] In the playoffs, the Celtics advanced to the Eastern Conference Finals for the third time in Brown's four years in the NBA following series victories over the Philadelphia 76ers and Toronto Raptors in four and seven games, respectively.

[64][65] Two days later, in a 124–104 victory over the Denver Nuggets, Brown and Tatum broke the record by both scoring 30 points with over 60% shooting from the field.

[66] On May 3, in Game 2 of the Eastern Conference Semifinals, Brown scored 25 of his 30 points in the first half while also recording six rebounds, six assists, and two steals in a 109–86 victory over the reigning-champion Milwaukee Bucks.

[68] On May 21, in Game 3 of the Eastern Conference Finals, Brown scored a playoff career-high 40 points on 14-of-20 shooting from the field in a 109–103 loss to the Miami Heat.

[70] During Game 1 of the 2022 NBA Finals on June 2, Brown posted 24 points, seven rebounds, and five assists in a 120–108 comeback victory over the Golden State Warriors.

[75] On December 13, Brown posted 25 points, a season-high 15 rebounds, five assists, and three steals in a 122–118 overtime victory over the Los Angeles Lakers.

[78] On January 11, 2023, Brown scored a then-season-high 41 points on 15-of-21 shooting from the field and grabbed 12 rebounds in a 125–114 victory over the New Orleans Pelicans.

[90] On January 22, 2024, Brown recorded his third career triple-double with 13 points, 11 rebounds, 10 assists, and three steals in a 116–107 victory over the Houston Rockets.

[98][99] During Game 1 of the 2024 NBA Finals on June 6, Brown had 22 points, six rebounds, three blocks, three steals, and two assists in a 107–89 victory over the Dallas Mavericks.

Brown became the second Celtic with 30+ points, 8+ rebounds, and 8+ assists in an NBA Finals game, joining John Havlicek (1968).

They also set the record for the most 25+ point games by a Celtics duo in postseason history, surpassing Larry Bird and Kevin McHale (17).

[103][104] Brown is primarily a vegetarian and his interests include Spanish language, history, meditation, philosophy, playing instruments, and anime.

In recent years, he has spoken on the importance of education and technology at Harvard University, MIT, and his alma mater, Berkeley.

[109] Through his work with MIT and his 7uice Foundation, Brown has taken a strong interest in tackling education and income inequality, among other social advocacy initiatives.

[110] He was offered an internship with NASA, was the youngest person to ever hold a lecture at Harvard, and was in the middle of a robotics class when he learned that his agent had secured him the largest contract in NBA history.

[111] Brown has a YouTube channel where he has posted several documentary-style video series depicting his life during the season and off-season workouts.