While playing college basketball for the Creighton Bluejays, McDermott led the nation in scoring in 2013–14 and was a three-time consensus first-team All-American.

He was the consensus national player of the year as a senior in 2014, and finished his college career with the fifth-most points in NCAA Division I men's basketball history.

[3] McDermott led the Bluejays to the 2011 College Basketball Invitational, where they made it to the best of three final series, ultimately losing to Oregon.

His 801 points, 307 field goals, and 48.6 percent shooting accuracy from three-point range were all school records for a single season.

[11] He won the Big East Player of the Year award, as well as earning First-Team All-American honors by U.S. Basketball Writers Association for the third time.

[12] McDermott was also the consensus national player of the year, winning all major awards (Wooden,[13] Naismith,[14] AP,[15] NABC,[16] USBWA,[17] and Sporting News[18]).

[19] At the end of his college career, he ranked fifth on the all-time NCAA Division I scoring list, with 3,150 points, which passed basketball Hall of Famer Larry Bird.

[22] On July 22, 2014, he signed his rookie scale contract with the Bulls after averaging 18.0 points, 4.0 rebounds and 2.8 assists per game during the 2014 NBA Summer League.

[25] Despite his promising debut, McDermott did not manage to eclipse 12 points before being ruled out indefinitely on December 1 due to a knee injury.

[28][29] In July 2015, McDermott re-joined the Bulls for the 2015 NBA Summer League, where he averaged 18.8 points and 4.4 rebounds in five games, impressing new head coach Fred Hoiberg.

[31] McDermott's Summer League form carried over into the regular season, with Hoiberg giving him plenty of game time off the bench.

[41] As a result, McDermott missed the next nine games, and on December 5, he was assigned to the Windy City Bulls of the NBA Development League for conditioning.

[42] He was recalled two days later[43] and made his return to Chicago's line-up on December 8, scoring eight points in a 95–91 win over the San Antonio Spurs.

[46] On February 23, 2017, McDermott was traded, along with Taj Gibson and an unprotected 2018 second round draft pick, to the Oklahoma City Thunder in exchange for Joffrey Lauvergne, Anthony Morrow and Cameron Payne.

[47] On March 18, 2017, McDermott had his highest-scoring game with the Thunder, going 8 of 9 from the field, including 4 of 5 from three-point range, to finish with 21 points in a 110–94 win over the Sacramento Kings.

[48] On September 25, 2017, McDermott was traded, along with Enes Kanter and a 2018 second-round pick, to the New York Knicks in exchange for Carmelo Anthony.

[49] In his debut for the Knicks in their season opener on October 19, 2017, McDermott scored four points on 2-for-5 shooting in a 105–84 loss to his former team, the Oklahoma City Thunder.

[64] Following the close of his freshman year at Creighton, McDermott was selected to the U.S. team sent to Riga, Latvia for the 2011 FIBA Under-19 World Championship.