Lyrically, the song discusses the artists' lifestyle and explores the theme of excessive fame and trust issues.

[16] Sheldon Pearce of Pitchfork deemed the song a combination of "some of the least interesting raps you could possibly imagine" and "a downer that won't quit", writing that it "uses concepts that have been played out in hip-hop for years".

[17] Patrick Hosken of MTV News opined that the song "finds a late-night vibe that, away from the madness of crunching guitars, unfolds like a chill celebration of luxury".

[18] Mitch Findlay of HotNewHipHop wrote that it "continues the formula set by" Post Malone's previous single "Rockstar", and that they share "a few melodic similarities", describing "Psycho" as "more subdued" in comparison.

[20] The official music video for "Psycho" was released on March 22, 2018, on Post Malone's Vevo YouTube channel.