Released on 7 April 2017 by Columbia Records, it was first written by Jeff Bhasker, Mitch Rowland, Ryan Nasci, Alex Salibian, while Styles gets writing credits for contributing.

[4] By the end of 2015, four new songs written and performed by Styles were registered on the ASCAP online database, which was believed to be for his potential debut solo album at the time.

[6] In February 2017, the CEO of Columbia Records, Rob Stringer, revealed that the album was close to being finished and called it "authentic".

[9] The same report also hinted that the lead single would be released in late April or early May and sounded "like it would be a smash in any decade".

[8] The same month, US radio host Elvis Duran accidentally revealed during his show that Styles' debut single would be released on 7 April 2017.

Rowland played guitar and drums, Nasci the bass, and Bhasker the piano, keyboard and lap steel parts.

[21] Styles explained to Rolling Stone that "The song is written from a point of view as if a mother was giving birth to a child and there's a complication.

A writer from USA Today humorously described Styles as "auditioning to be Marvel Comics next superhero or in a new biblical epic".

Billboard's Gil Kaufman wrote, "Styles appears to be both showing his range and making a clear effort to step boldly away from the manufactured, plastic pop of his past".

Kaufman opined that the song "rakes in influences from Pink Floyd and David Bowie to Queen, Spacehog, Suede, Coldplay, the Beatles, Eric Carmen and Prince".

[16] Also for Billboard, Jason Lipshutz described the song as "resolute, determined, wholly committed to its messaging and sound, radio trends be damned.

[37] Other critics have compared the song to the music of American indie rock band the Walkmen,[38] to Fun's "We Are Young" and Coldplay's "The Scientist",[39] and to Britpop anthems like Blur's "Tender" or the Verve's "Bitter Sweet Symphony".

[40] Brittany Spanos of Rolling Stone asserted that "Sign of the Times" "aligns" "with the Seventies-inspired pop-rock of One Direction's more recent albums like Made in the A.M.".

[41] Anjali Raguraman from The Straits Times considered it the "strongest" track on the album, saying "the conviction of his delivery is beyond his years".

[43] Since the song was released on the 30th anniversary of Prince's Sign o' the Times, Spin's Andy Cush commented, "it's clear that this is Styles's attempt to distinguish himself as an artist with real depth.

Cush added that the song "has only those three chords, and it goes straight for cruising altitude with an onslaught of cymbals and guitar on the first chorus, expecting you to be moved without pausing to consider why".

[69] On 21 April, Harry appeared on the BBC's The Graham Norton Show, for his debut solo performance in his native UK.