Polachek played the song live on her Heart is Unbreaking US tour in late 2021, and on several fall 2021 festival dates before the single was officially released.

A September 2021 New Yorker profile on Polachek explained the song's backstory as follows:[…] One day, Danny L Harle sent her a beat that he'd written, and Polachek heard a melody out of nowhere, oceanic and potent, and started jotting down psychedelic images: a headless angel, an overflowing cup, a pearl inside an oyster.

Pitchfork named the song a 'Best New Track', and in a review contributor Gio Santiago wrote that "Billions" is "a lucent pathway towards a new era for the pop auteur".

[4] The Fader's Jordan Daville wrote that, with "Billions", Harle and Polachek created "a kind of divine symmetry from its elements, channeling Pure Moods-era new age into something utterly splendid".

[5] Kat Bouza from Rolling Stone described "Billions" as "a trip-hop inspired, hallucinogenic epic that finds the songwriter expanding upon the inventive production style perfected on her critically acclaimed 2019 album, Pang.