It was released by Darkroom and Interscope Records as the sixth single from Eilish's debut extended play (EP), Don't Smile at Me (2017).

A pop track with jazz-influenced instrumentation, the song was heavily inspired by boys who broke Eilish's heart.

[3] Claire Ruder writing for Earmilk praised TroyBoi's remix, saying it "was able to successfully transform a tempo-changing short-and-sweet pop song into bass-laden and explosive EDM."

And further mentions "'MyBoi,' turns chopped vocals from Billie into an instrument for the chorus of the track, paired with intricate layers of hi-hats, heavy kicks, and bass.

[7] The song soon becomes more upbeat while maintaining the heaviness of the intro: My boy's being sus' and he don't know how to cuss/He just sounds like he's tryna be his father (Who are you?

[6][7] "My Boy" was praised by Insider's Callie Ahlgrim, who called the track "slow" and "mysterious" and felt its chorus "is so springy and elastic that it's almost distractingly danceable.