[2][3] The song appears on the deluxe edition of Lavigne's seventh studio album Love Sux, as an official track in her Greatest Hits compilation.

[4] The release of "I'm a Mess" was announced on October 24, 2022, in a livestream featuring Yungblud cutting Lavigne's hair with a snippet of the song playing.

[5] "I'm a Mess" is a "a slow-burning guitar ballad" which "begins with Lavigne singing about an absent loved one", and "drums kick in later ahead of Yungblud's verse, which hears the Doncaster artist say his life "hasn't been the same since that night".

[12] The music video for "I'm a Mess" was released the same day as the single, and features Lavigne "getting reflective in the sunshine while [Yungblud] wanders around a gloomy London, before they meet up at the end for a performance of the song.

"[8] "I'm a Mess" was performed live on June 21, 2024, during Avril Lavigne's concert at the Pinkpop Festival as part of her Greatest Hits Tour, with the song being a surprise track featuring Yungblud.