As a junior, he returned to the starting lineup as the Bruins' point guard, when he was named a third-team All-American and received first-team all-conference and all-defensive honors in the Pac-12.

[5] He averaged 28.9 points, 8.5 rebounds, and 6.0 assists as a junior before being named both CIF Southern Section IV-A and Los Angeles Daily News Player of the Year honors.

[8] Averaging 25 points, 8.5 rebounds, 4.5 assists and 2.5 steals, he led Campbell Hall to its first sectional and California regional final since 2008, and shared Daily News Player of the Year honors with Bennie Boatwright of Valley Christian.

[1][10][11] Holiday entered the University of California, Los Angeles, with a reputation as a tenacious defender capable of applying full-court pressure.

[12] After an exhibition game against the Bruins, Cal State Los Angeles coach Dieter Horton admired his ability to disrupt, calling him a "little Tasmanian devil on defense".

[13] Holiday and fellow recruit Prince Ali brought needed depth to UCLA, who were thin at guard during the previous season.

He hoped the freshman could help ease ball-handling duties from incumbent point guard Bryce Alford, the coach's son, who was more effective catching the ball and shooting.

[14] In a scrimmage against San Diego State which Bryce Alford mostly missed due to an injury, Holiday's performance against a strong Aztecs defense prompted their coach, Steve Fisher, to call him "by far the best player on the floor".

[17] In the season opener, Holiday and Tony Parker had six turnovers apiece as UCLA turned the ball over 23 times in an 84–81 overtime loss to Monmouth.

[19] On January 9, 2016, he made the go-ahead three-point field goal with just over a minute remaining in an 81–74 win over Arizona State,[20] which helped UCLA avoid falling to 1–3 in the Pac-12 Conference for the first time in almost 20 years.

[22] Holiday started all 32 games during the season, averaging 10.3 points while leading the team in both steals (1.4) and three-point field goal percentage (41.9), which also ranked sixth in the Pac-12.

[1] In 2016–17, Holiday was moved to the bench and became the Bruins' sixth man as star freshman point guard Lonzo Ball joined seniors Alford and Hamilton in the starting lineup.

[25] He did not complain about his new role, and thrived while continuing to receive starter-like playing time as the Bruins frequently used a four-guard lineup.

With Ball slowed by a hip injury in their opening game against Kent State, Holiday had 15 points and a career-high 11 assists off the bench to help the Bruins win 97–80.

[38][39][40][41] Against Wisconsin in the CBE Hall of Fame Classic, Holiday made a layup with 0.8 seconds left in the game to give UCLA a 72–70 win.

UCLA blew a double-digit lead in the second half when the Ducks went on a 13–0 run after Holiday went to the bench in foul trouble.

Coach Alford stated that Holiday's value was underscored by the team's plus–minus when he is out of the game, and he called his star guard a candidate for Pac-12 Player of the Year.

[55] In UCLA's Pac-12 Tournament opener, Holiday scored 34 points for the second consecutive game and added eight assists and seven rebounds to lead an 88–77 win over Stanford.

[55] After the season, Holiday decided to forgo his senior year at UCLA and declare for the NBA draft, where he was projected to be as high as a mid-to-late first-round selection.

[72] The Pacers went back to their earlier rotation without Holiday,[72] but he returned in the end of January 2019 after Oladipo suffered a season-ending right knee injury.

[77] During the offseason, Holiday was joined on the Pacers by his older brother Justin, who signed a one-year contract as a free agent.

[88] On August 6, 2021, Holiday and the rights to draft pick Isaiah Todd were traded from Indiana to the Washington Wizards in a multi-player, five-team deal.

[89] Against his former team on October 23, he started in place of an injured Bradley Beal and scored seven points in 25 minutes in an overtime win against the Pacers.