[1] Collier demonstrates his harmonic expertise in lectures and master classes, particularly with his detailed analyses of songs like Stevie Wonder's "Sir Duke" and his own music.

In 2014, Collier signed with Quincy Jones's management company and began working on his one-man, audio-visual live performance vehicle, designed and built at the MIT Media Lab by Ben Bloomberg.

[14] At the same time he was performing as a treble singer in classical roles, such as one of the three boys in Mozart's The Magic Flute and Miles in Benjamin Britten's The Turn of the Screw, which influenced his use and understanding of harmony.

His musical activity caught the attention of Quincy Jones,[10] who flew Collier to the Montreux Jazz Festival where he was introduced to Herbie Hancock.

Central to the show was a custom-built vocal "Harmonizer" instrument that enabled Collier to sing multi-voice harmonies in real-time.

In July 2015, Beats by Dr. Dre asked Collier to provide music for "The Game Starts Here" England Rugby World Cup campaign commercial.

[22] Collier recorded an a cappella version of the hymn "Jerusalem" for the commercial, which was shown on national television before each England match.

[23] In late 2015, Collier began preparing his debut album In My Room after performing with WDR Big Band in a concert in Cologne, Germany.

[24][25] He wrote eight of the eleven songs and arranged, recorded and produced the album in the music room of his family home, playing every instrument himself.

Collier received more than 130 melodies and donations, including from British jazz artist Jamie Cullum, Ben Folds, Herbie Hancock, and Kevin Olusola of the a cappella group Pentatonix.

"[30] On 22 August, he took part in a Quincy Jones tribute concert at the BBC Proms in the Royal Albert Hall in London, in which he performed, among others, his orchestral arrangement of his original song "In The Real Early Morning" with the Metropole Orkest, conducted by Jules Buckley.

[31][32] In December 2016, Collier collaborated with 150 students at MIT to produce a live concert in Kresge Auditorium, titled "Imagination Off the Charts", playing alongside orchestral arrangements of his repertoire.

[42] Collier toured internationally for two and a half years between 1 July 2015 and 18 December 2017,[43][44] while hosting masterclasses and performances with orchestras and big bands around the world, including the Metropole Orkest.

On 19 July, "Jacob Collier and Friends" performed as part of the BBC Proms at the Royal Albert Hall in London.

1 was released in full on 7 December,[47] and featured the singles "With The Love in My Heart", "Ocean Wide, Canyon Deep" and "All Night Long".

[51][52] The same year, Collier provided backing vocals for several tracks on Coldplay's eighth studio album, Everyday Life.

"He Won't Hold You" won Best Arrangement, Instrumental and Vocals,[56] making Collier the first British artist to win a Grammy Award for each of his first four albums.

[61] Collier received two nominations at the 65th Grammy Awards: Best Arrangement, Instruments And Vocals for his single “Never Gonna Be Alone” and Album Of The Year for his contributions to Music of The Spheres.

[67] The singles include "Little Blue", featuring Brandi Carlile;[68] "Wherever I Go", "Witness Me", "Mi Corazón", and a cover of Paul Simon's "Bridge Over Troubled Water".

[71] He also performed at the Grammy Awards ceremony, playing "Both Sides Now" with Joni Mitchell, Brandi Carlile, Allison Russell, SistaStrings, Blake Mills, and Lucius.

[73] His more recent releases, which were also uploaded to streaming services, featured unconventional musical elements such as microtonality and complex chords and progressions, as well as sudden key- and time signature changes.