[4] He briefly attended Wheaton before transferring to Sidwell Friends School, where as a junior he averaged 20.6 points and 11.6 rebounds per game.

[8] A 2013–14 Big East All-Rookie Team selection, Hart averaged 7.8 points and 4.0 rebounds per contest as a freshman at Villanova.

[1] He did not shoot the ball particularly well, making 31 percent of his three-point tries, but possessed "amazing confidence," according to assistant coach Baker Dunleavy.

[13] On February 28, 2015, in the second half of a game against Xavier, Hart was hit in the mouth during a scramble for the ball, requiring stitches on his lip.

[9] As a sophomore, Hart was named the Big East's sixth man of the year at the conclusion of the regular season.

"He's the perfect sixth man because he can come in and play any position except probably point guard," head coach Jay Wright said.

[19] Hart led the Wildcats to reach number one in the AP Poll by climbing to the top of the 2015–16 NCAA Division I men's basketball rankings on February 8.

[24] Coming into his senior season, Hart's Wildcats were projected to win the Big East by the coaches and he was named Preseason Player of the Year.

[26] In November Hart scored a then-career high 30 points vs Wake Forest in a 96–77 win at the Charleston Classic.

[28] On March 11, 2017, in the regular season finale versus Creighton Bluejays Hart scored 29 points in a 74–60 win.

[32] In his first start on December 14, 2017, Hart recorded a double-double against the Cleveland Cavaliers, scoring 11 points and grabbing 10 rebounds.

[35] On March 28, 2019, the Lakers announced that Hart had undergone a successful ultrasonic debridement procedure on his right knee patellar tendon and was expected to miss the remainder of 2018–19 season.

[40] On March 12, Hart scored a career-high 44 points, along with 8 rebounds and 6 assists, on 15-of-21 shooting and 6-of-9 from beyond the arc in a 127–118 victory over the Washington Wizards.

[41] On November 7, 2022, Hart put up 12 points, nine rebounds, and eight assists, alongside a buzzer-beating, game-winning three in a 110–107 win over the Miami Heat.

[42] On February 8, 2023, the Trail Blazers reached an agreement to trade Hart to the New York Knicks for Cam Reddish, Ryan Arcidiacono, Sviatoslav Mykhailiuk, and draft considerations.

[44][45] On February 11, Hart made his Knicks debut, recording 11 points, four assists, and seven rebounds in a 126–120 win over the Utah Jazz.

[51] On March 18, Hart played all 48 minutes of a victory against the Golden State Warriors, joining Clyde Frazier and Jerry Lucas as the only players in franchise history to accomplish the feat.

He became the fifth player in Knicks franchise history to achieve consecutive triple-doubles, joining Richie Guerin, Jerry Lucas, Walt Frazier, and Micheal Ray Richardson.

[55] Hart was a member of the United States national team that competed in the 2023 FIBA Basketball World Cup.