[8][better source needed] His parents were supportive of his musical study, and he credits his father for frequently driving him into Dublin to perform at open mic nights when he was underage.

[11] Through busking, he was able to develop his sound, travelling to multiple major cities such as Dublin, Ireland and Boston, US to perform.

[6] In 2015, Kennedy uploaded the song "An Evening I Will Not Forget" to the streaming platform Spotify, with which he believed he was "really reaching people".

[11] He was also invited to open for Glen Hansard, whom he had previously met while busking in Dublin and stayed in touch with via text message.

"[24] In early 2020, in collaboration with other artists, Kennedy contributed his vocals to Songs For Australia, covering Matt Corby's "Resolution".

Following that event, Kennedy organized his own virtual concert, Sound Waves, in May 2020 in support of WHO's Solidarity Response Fund.

[27] On 6 September 2020, Kennedy played for the Soccer Aid charity match for the first time, joining other celebrities in raising money for UNICEF UK.

[32] GQ magazine described Kennedy as a "singer with a rich, reverbant voice, [with] epically emotive songwriting skills (think Ed Sheeran, but darker, more melancholy)".

[5] The New York Times, of his 2018 South by Southwest Festival performance, said he has "a grainy, melancholy voice that can crest with a howling rasp..."[33] He cites Ray LaMontagne, David Gray, Damien Rice and Glen Hansard as inspirations for his folk style.

[37] On 20 June 2023, Kennedy apologised after he used a term derogatory to Irish Travellers during an interview with the Canadian TV music channel Much.