Guitarist Michael Clifford first opened up about the third album and the upcoming single in an interview with Billboard in December 2017. He admitted: "We're at a point now where we're almost ready to put out our first single," as he promised that fans could expect it "really, really early in the new year". On 16 February 2018, the band posted a black and white picture featuring all members on Twitter, captioning it "Behind The Scenes 2018." They shared another tweet with the hashtag "#5SOS3ISCOMING" shortly afterwards, hinting at new releases. They also teased a few lyrics from the song and posted a GIF which says "We Want You Back". The song was officially announced on 19 February 2018, along with its release date, cover art, and a brief audio snippet. The song was released alongside the announcement of their worldwide promotional 5SOS III Tour dates. Drummer Ashton Irwin said of the song in an interview with Beats 1: "'Want You Back' articulates the band we were, we are now, and what we're gonna be, that's why I like it and that's why we picked it. We also made it with close friends like we've got Andrew Goldstein who we literally see every week. We party together, we confess our sorrows and happiness. We speak to this man everyday." The band told news.com.au that they are "super nervous" about the comeback song which will introduce their third album.
Critical reception
Madeline Roth of MTV News stated that the song "marks a huge departure from the band's raucous pop-punk roots". She found the band "opting for a slick, more polished pop sound on the new tune, which finds them reminiscing about an ex and wondering what went wrong". Althea Legaspi of Rolling Stone regarded it as a "pop-flavored track reflects on a lost love and captures the yearning that often follows a breakup". Hugh McIntyre of Forbes found the song "surprisingly slick, especially for a band that has pushed a narrative of being rowdy rock boys", and he noticed that the song was "more mature". Mike Wass of Idolator wrote that the band have abandoned "the pop/punk of their first two albums and dive head-first into slick, radio-friendly pop with a rhythmic edge". Rania Aniftos of Billboard deemed it an "apologetic pop track" and a "synth-y upbeat tune". Nicole Mastrogiannis of iHeartRadio opined that it "takes a step back from 5SOS's signature pop/punk vibes" and "playing up the guys' pop side a bit more".
The official music video was released on 27 March 2018. It features the members of the band performing in a colorful one-room set, depicting a scenario where the rules of gravity does not apply. The furniture can be seen fixed to the walls and ceiling as the band members remain on the ground while singing and playing their instruments. In some shots, they appear to be walking and sitting on the walls and ceiling. The video shows mostly full-room shots of the set and some closeup shots of the band members. The closeup shots of the band members' faces are often opaquely overlaid on the full-room shots.