Musically, the song is pop and R&B track with a jazz and neo soul-influenced melody, that was heavily inspired by Eilish being depressed.

[2] According to sheet music website Musicnotes.com, "Idontwannabeyouanymore" has a gentle lilt tempo of 57 beats per minute (BPM) and is played in the key of E minor.

"[8] The song starts off with a piano, before Eilish begins to sing about struggling with self-doubt while dealing with how society wants her to be.

Eilish refers to models and people's tendencies to judge someone for what the clothes they wear: "If teardrops could be bottled/There’d be swimming pools filled by models/Told the tight dress is what makes you a whore.

[9] According to Libby Torres of Insider Eilish sings about being "determined to break out on her own and become her own person", but the chorus suggests that she feels complicit or to blame in her failed relationship with herself.

[4] In her review for Earmilk, Jess Bartlet stated the track has a "vocal vulnerability and innocence that wouldn't sound out of place in Quentin Tarantino's Kill Bill".

[11] Insider's Libby Torres remarked that "Idontwannabeyouanymore" when combined with her "airy vocals" and "gently flowing piano", it makes the track a "perfect song".

[14] Following the release of Eilish's debut studio album When We All Fall Asleep, Where Do We Go?, "Idontwannabeyouanymore" rose to number 96 the chart and stayed there for three weeks.

[23] In the minimalistic visual, it portrays a silver-haired Eilish in an all-white room talking to her reflection in a mirror about how she hates herself.

[22] Shweta Patokar writing for Republic World commented that what makes the video scary is how "close it is to reality".

[34] In November 2019, The Devil Clefs, an a cappella group from Arizona State University, covered the track.

[36] In his audition for America's Got Talent on July 15, 2020, Australian masked singer Sheldon Riley covered the track.