He finished his high school career at Prolific Prep in Napa, California, and he chose to forgo college basketball to join the NBA G League Ignite team in its inaugural season.

Green has won three gold medals with the United States at the junior level and was named Most Valuable Player (MVP) of the 2018 FIBA Under-17 World Cup.

[21][22][23] He received offers from many NCAA Division I basketball programs, including Arizona, Florida State, and USC before turning 15 years old.

[1][36] Many thought the Rockets would take USC big-man Evan Mobley with the 2nd overall pick but Houston took Green to pair aside with Kevin Porter Jr in the backcourt with James Harden being dealt during the season .

[37] On August 8, he made his summer league debut in a 84–76 win against the Cleveland Cavaliers where he posted 23 points, five rebounds, and two assists in 30 minutes.

[44] Unfortunately for Green, he started out his rookie season suffering with a hamstring injury on his lower left leg after a home game win against the Chicago Bulls and been sidelined out of the rotation for a while.

[54][55] In his second game of the season, Green played 35 minutes with a record of 33 points with four threes, five rebounds, two assists, and a steal in a 129–122 loss to the Grizzlies.

[56] On November 7, 2022, scored 34 points in a win against the Orlando Magic, making him the sixth guard in NBA history to score at least 30 points ten or more times before turning 21, joining other elite guards in Luka Dončić, Devin Booker, Anthony Edwards, LaMelo Ball, and Kyrie Irving.

[60] On January 15, 2023, the NBA suspended Green along with teammate Jae'Sean Tate for one game without pay for leaving the bench area during an altercation between the Rockets and the Sacramento Kings two days earlier.

[67][68] On January 24, 2024, Green and his teammate Alperen Şengün became the first duo in NBA history to score 30-plus points and 10-plus rebounds at 21 years or younger in a 135–119 win against the Los Angeles Lakers.

[73] On January 13, 2025, Green matched his career high with 42 points by shooting a best 72.2% from the field in a home game win against the Memphis Grizzlies.

[74] Green represents the United States internationally but has also shown interest in playing for the Philippines in the future due to his partial Filipino background.

[76] He was named MVP of the 2018 FIBA Under-17 Basketball World Cup in Argentina after averaging a team-high 15.7 points, 2.3 rebounds, and 1.7 assists per game and winning the gold medal.

[77] Green won another gold medal with the United States at the 2019 FIBA Under-19 Basketball World Cup in Heraklion, Greece.

He is known for his elite athleticism, handling skills, and versatile scoring abilities that makes him an on-and off-the-ball threat in a half-court setting and in transition.

He has drawn comparisons to Zach LaVine, Ray Allen, Kelly Oubre Jr., Bradley Beal, Clyde Drexler, and Kobe Bryant.

[86][87][88] His step-father, Marcus Green, was a basketball teammate of NBA player DeShawn Stevenson at Washington Union High School in Fresno.