After five games, his college career was cut short by a meniscus injury, which prompted him to leave the team to prepare for the NBA draft.

[2] In third grade, he attended basketball camps in Valparaiso, Indiana led by Bryce Drew, who would become his college coach at Vanderbilt.

[6] In his freshman season, he averaged 17 points, 1.3 rebounds, and 2.7 assists per game, leading his team to a Tennessee Secondary School Athletic Association (TSSAA) Division II-AA state championship.

[8] On December 23, 2015, as a sophomore, he claimed most valuable player (MVP) honors at the King of the Bluegrass Holiday Classic, after scoring 23 points versus Fairdale High School in the title game.

[10] From his sophomore to junior year, he grew 2½ inches, and by his fourth season with Brentwood Academy, he was ranked the best point guard in the 2018 class by recruiting service 247Sports.

[13] On November 13, 2017, he committed to play college basketball for Vanderbilt, drawn there by its proximity to his home and head coach Bryce Drew.

[14] He averaged 27.6 points, 5.0 rebounds, 4.3 assists and 1.7 steals and secured a fourth straight state title for Brentwood Academy, tying the TSSAA record.

[15][16] Garland joined the MaxPreps High School All-American third team and became the only player other than Brandan Wright to win Tennessee Mr. Basketball on three occasions.

[23] Four days later, Vanderbilt head coach Bryce Drew revealed that Garland would be sidelined for the remainder of the season with a meniscus injury.

[29] On October 23, 2019, Garland made his debut in NBA, starting in an 85–94 loss to the Orlando Magic with eight points, two rebounds, five assists and a steal.

[34] On December 23, 2020, Garland made his season debut for the Cavaliers, recording 22 points, six rebounds and six assists in a 121–114 win over the Charlotte Hornets.

On January 12, 2022, Garland recorded his first career triple-double, putting up 11 points, 10 rebounds, and a then career-high 15 assists, in a 111–91 win over the Utah Jazz.

[41] The following game, Garland and the Cavaliers lost to the Atlanta Hawks,[42] meaning that despite doubling their previous season's win total from 22 to 44 and finishing with the eighth best record in the eastern conference,[43] they would not advance to the postseason.

He became the fourth Cavaliers player to score 50, joining LeBron James (nine times), Kyrie Irving (twice) and Walt Wesley (once).

[50] On February 5, 2025, Garland recorded 25 points, five assists and hit a 31-foot 3-pointer at the buzzer to give the Cleveland Cavaliers a 118–115 win over the Detroit Pistons.