“COMPLETE MESS” follows 5 Seconds of Summer’s anniversary single “2011” and is the lead single of their fifth studio album 5SOS, released on September 23rd 2022.

An informal announcement of the song was made on February 18th 2022, when the band sent a magazine to a fan and retweeted a tweet she made about the song’s title and release date. However, the official announcement was made via Instagram post a week later, on February 25th, alongside the official cover art of the song.

5 Seconds of Summer have been teasing the song for a while before its release. The first two snippets were via 5SOS' TikTok, on February 19th and February 20th. A few days later, they started posting the snippets on their Twitter. The first ones, on February 25th, 26th, 27th and 28th, were all instrumental. On March 1st, a day before the song’s release, the band posted the last snippet, that revealed part of the lyrics for “COMPLETE MESS”.