Declan McKenna was born in Enfield, Greater London,[3] on 24 December 1998[4][5] and grew up in Cheshunt, Hertfordshire,[6] where he attended St Mary's Church of England High School.

[4][8] He later studied for his A-levels in English Literature, Philosophy and Ethics, and Sociology, but stopped after a few months after his music career began to consume too much of his time.

"[11] "Brazil" garnered McKenna widespread attention, as many sports commentators found the song to be a commentary on the emerging FIFA corruption scandal.

[15] McKenna spent the remaining months of 2015 playing a wide range of British and Irish music festivals and concerts in venues throughout London.

[4] In an interview with Sound of Boston, McKenna explained that the title of the song came from "the idea of using the lyric paracetamol was a way of comparing the belief that someone can be cured from who they are, via therapy, to an everyday painkiller.

Although it was not likely to receive radio airplay or top out the charts, Wilkinson argued, the song showed that McKenna was not just another "UK indie troubadour, a little bit oikish and with a nifty talent for mainstream melody", but rather a solid and accomplished songwriter who can deliver "bruised and vulnerable" vocals.

[6] Jon Lyons of the music Web site ThisNewBand.com said the song showed a maturity that clearly indicated McKenna was not "just a teen dream or a one hit wonder.

[22] McKenna stayed quiet for much of 2016, writing songs in his bedroom for his debut album,[23] but released "Bethlehem" that year, and in late August, his fourth single, "Isombard", which treated right-wing media.

[31] McKenna appeared on BBC Music's "Sound of 2017" list at the end of 2016, after releasing the two EPs Stains and Liar that year.

[citation needed] On 19 August 2019, McKenna released the song "British Bombs", which criticises UK foreign policy.

[43] In July 2021, he released the single "My House" with an accompanying music video, a song he described as being about "remembering what it is to be lost in your thoughts in a good way".

[47] McKenna writes his own songs, but is supported by a band on tour currently consisting of Isabel Torres (guitar), Henry Pearce (keyboards), Linus Fenton (bass) and Ben Limmer (drums),[48] although he has previously played all of his own instruments.

[8] Matt Wilkinson at NME called it "one of the best songs" of 2015, and had high praise for McKenna's second single, "Paracetamol", as well.

[6] Jon Lyons of ThisNewBand.com called "Brazil" "a catchy song no doubt", and also noted that it was "a sharp critique on sports, money and power.

Matt Wilkinson called McKenna's London gigs surprisingly good, if "rough around the edges".

[6] Jon Lyons has observed that as of November 2015, McKenna's songs seemed to indicate an artist still experimenting with bands and styles of music which have influenced him.

"[21] Andy Welch, music critic for the Bristol Post, said McKenna was "one to watch", displaying "lots of early, ragged promise".

[52] After adopting a somewhat glam rock visual style for his live performances (which included use of eye makeup and glitter),[12] McKenna addressed questions about his sexuality with Attitude magazine by declining to label himself, saying, "I'm young.

[57] In July 2020, he signed an open letter to the then-UK Equalities minister Liz Truss calling for a ban on all forms of LGBT+ conversion therapy.