According to Skylab, the album's name (and the trilogy it is part of) was inspired by a controversial statement given by fellow musician Lulu Santos in late December 2017, in which he stated "MPB was de-evolving into its 'anal phase'", alluding to the then-recently released music video for Anitta's "Vai Malandra".

[4][5] On April 2, 2018, Skylab uploaded to his SoundCloud page a brief 30-second teaser of one of the tracks that would be featured on the album, "Dedo no Cu e Gritaria",[6] which was inspired by an obscure Internet meme originated in Brazilian shitposting communities.

[7] The track "Eu Durmo Pouco pra Ficar com Sono" premiered live on Danilo Gentili's late-night talk show The Noite on April 24, 2018.

[8] A show promoting the album's release took place at the Baden Powell Room of the Teatro Copacabana in Rio de Janeiro on April 25, 2018.

[9] Ipitácio Oliveira of radiocultfm gave O Rei do Cu a positive review, calling it a "lyrical" album "less psychedelic than its predecessors", what makes it "more accessible to new listeners".