The album was released to positive reviews, with critics praising the lyrical maturity and the sound change from their previous work.

[23] The band performed their lead single "Want You Back" on The Tonight Show Starring Jimmy Fallon on 11 April.

[29] On 1 August, the band released the Spotify-exclusive recording of their "Lie to Me" track, a stripped back version which was made available for streaming, along with a cover of Post Malone's "Stay".

[30] Apple Music released the "On the Record: 5 Seconds of Summer – Youngblood" documentary, featuring interviews about the making of the album.

Apple Music also organised a one-night show in New York on the release date of the album to showcase the short film.

Prior to the album's release, the band embarked on the promotional 5SOS III Tour, which took place at 26 intimate concert venues worldwide.

[39] The tour was met with positive reviews, with Billboard praising the show for its "impressive" and "electric energy"[40] The album's lead single, "Want You Back", was released via Capitol Records on 22 February 2018.

[46] Brittany Spanos of Rolling Stone also commented on the transition and wrote that, "pop-punk is not a genre that's meant to carry a band through a full career.

Instead, Youngblood goes full pop, leaning into some Eighties inflection and foregoing the bratty, DGAF ethos of their earlier work."

The snottiness of pop-punk highlighted their natural humor, and while they've certainly grown as musicians, singers and writers, a bit of that goofy charm is missing".

[1] Nick Hasted and Ilana Kaplan of The Independent opined that "the grit the band had on their first two records is definitely missed" but that "fans will probably still enjoy the sounds of 5SOS".

[2] Atlas Artist Group praised the album, referring to it as a "surprising and welcome departure from the sound that made them famous" and that the record "boasts solid tracks and hardly any filler."

"[22] Ryan Ward of The Irish News named the record an "unmistakably pop album [that] is suitably edgy and reflective in parts" while writing that they "strengthen[ed] their position as the definitive pop-rock band of recent years" with Youngblood.

[49] Youngblood was a commercial success and debuted at number one in Australia, becoming 5 Seconds of Summer's third number-one album in their home country.

[52] It also led to 5 Seconds of Summer being the first band (not vocal group) to have their first three full-length studio albums debut atop the Billboard 200.

[8] "Youngblood" sold over five million adjusted copies in the first six months of its release[9][10][11] and is the most streamed Australian song of all time on Apple Music.