[24] Smith attended the Anglican St Mary the Virgin church, Saffron Walden, with family members, as a youth.

The first song on the EP, titled "Safe with Me", is produced by Two Inch Punch and was first broadcast on MistaJam's BBC Radio 1Xtra show on 24 July 2013.

[28] Smith released the Disclosure, Nile Rodgers, and Jimmy Napes collaboration "Together" on 25 November 2013 as the only single from Settle: The Remixes.

It was announced on 16 December that Smith's debut studio album, titled In the Lonely Hour, would be released on 26 May 2014 through Capitol Records.

[36] A live version of album track "I've Told You Now", performed at St Pancras Old Church, was made available as a free download as part of an Amazon.com promotion on 27 December 2013.

[37] The album track "Make It To Me", co-written by Howard of Disclosure and Jimmy Napes, was made available as a free download as part of an iTunes Store promotion on 13 January 2014.

[33] On 20 January 2014, Smith made their American television debut performing "Latch" with Disclosure on Late Night with Jimmy Fallon.

[43] Smith performed "Stay With Me" live at the 2014 MTV Video Music Awards on 24 August at The Forum in Inglewood, California.

[44] On 15 November 2014, they joined the charity group Band Aid 30 along with other British and Irish pop acts, recording the latest version of the track "Do They Know It's Christmas?"

at Sarm West Studios in Notting Hill, London, to raise money for the 2014 Ebola crisis in Western Africa.

[45] In 2015, it came to light that singer Tom Petty, noting similarities between "Stay with Me" and his 1989 hit song "I Won't Back Down", had negotiated an out-of-court settlement with Smith in October 2014.

[49] The same month, Smith recorded another version of the song, featuring John Legend, for the British charity telethon Comic Relief, which reached number one in the UK.

[52] On 8 September 2015, Smith and Jimmy Napes confirmed that they had composed "Writing's on the Wall", the theme song to Spectre, the 24th James Bond film.

[57] Smith performed "Writing's on the Wall" at the Academy Awards on 28 February and, along with Napes, collected the prize for Best Original Song.

[58] In their acceptance speech, Smith referenced an article by Ian McKellen published before the awards ceremony that claimed no openly gay man had won an Oscar for Best Actor; Smith misquoted McKellen as saying that no gay man in general had won an Oscar.

This was quickly discredited by openly gay recipient Dustin Lance Black,[59] but McKellen mentioned that the error "doesn't detract" from Smith's achievement.

[62][63] On 20 March 2018, Smith started the Thrill of It All Tour, which visited Europe, North America, Asia, New Zealand, Australia, and South Africa until 2019.

In January 2019, Smith released the song "Dancing with a Stranger" with Normani as a single and it reached the top ten in the UK, the US and other countries.

In February, Smith performed a medley of songs alongside Calvin Harris, Rag'n'Bone Man and Dua Lipa at the 2019 Brit Awards held at the O2 Arena in London.

[73] The same year, Smith recorded a cover of "You Will Be Found", in collaboration with Summer Walker, for the soundtrack album of the 2021 film adaptation of Dear Evan Hansen.

[93] Smith described Robyn as a major influence on Love Goes and said that they listened to her "nonstop" while making the album because they "could dance and be sad at the same time and feel empowered".

[92][94] Speaking to Rolling Stone in January 2016, Smith named Whitney Houston and Mariah Carey as the greatest R&B voices.

[98] In an October 2017 interview for Attitude magazine, Smith spoke of the impact of their close friend Ed Sheeran's success: "It makes you push yourself.

[100] Smith places a lot of emphasis on their voice and stated they tried to make it the main element of their debut album In the Lonely Hour.

[101][102] Jessica Robertson of The Fader considers that Smith represents "a return of the virtuosic vocalist in popular music", in the vein of Whitney Houston and Luther Vandross.

[109] In October 2017, Smith came out as genderqueer,[110] saying, "I feel just as much a woman as I am a man"[108] and speaking of a period in their youth where they "didn't own a piece of male clothing and would wear full makeup while attending school".

[111][112] In September 2019, they came out as non-binary and changed their pronouns to they/them, stating, "After a lifetime of being at war with my gender I've decided to embrace myself for who I am, inside and out..."[7][8] Smith has struggled with body image issues since preteen years and been open about this in interviews.

[114][non-primary source needed] Smith confirmed their then-two-year-long relationship with fashion designer Christian Cowan to the New York Times in May 2024.