[7][8] "Bitches Broken Hearts" was written by the singer, her brother Finneas O'Connell and Emmit Fenn.

[3][10] According to sheet music published at Musicnotes.com, "Bitches Broken Hearts" has a moderately fast tempo of 120 beats per minute (BPM) and is played in the key of A minor.

[11] Lyrically, the song delves into the aftermath of a breakup, Eilish pretends that she no longer needs or cares about her former lover: “You can pretend you don’t miss me/You can pretend you don’t care/All you wanna do is kiss me/Oh, what a shame, I’m not there.”[10][12] Eilish continues to her lovers' incompatibility, calling them "suicide and stolen art"; she also knows they'll both eventually move on and start to meet new people: "Somebody new is gonna comfort you/Like you want me to/Somebody new is gonna comfort me/Like you never do".

[10] Kirsten Spruch of Billboard commented that the song has "subdued like a lot of the siblings' work" but has "a tropical flare, which makes it a great Eilish cut for those looking for something a bit more relaxing".

[13] Laurence Day of The Line of Best Fit viewed the song as a "intimacy and free-flowing energy of a raw demo take" and "it's still got all of Eilish's sensational vocal power".