
"Deja Vu" is about an on-and-off-again love where "Malone helms sluggish, lovesick verses". In a different comparison, Dana Getz of Entertainment Weekly wrote that it "features a slow fizz, cha-cha inflected beat akin to a drowsier take on Drake's ' One Dance '". In particular, The Fader 's David Renshaw said it "has an almost 'Hotline Bling'-esque tempo", while Madeline Roth of MTV News, Danny Schwartz of HotNewHipHop, and Billboard 's Colin Stutz noted similarities between the two with the song's start. Several critics made comparisons to Drake's " Hotline Bling" in regards to the song's sound. It opens with a church organ that backs the track. "Deja Vu" is a laid-back pop song with a deep R&B groove involving "wistful, detuned guitar riffs". "Deja Vu" leaked online a day before its official release. Bell referred to the session as a high-pressure situation that "kept on toes" while he engineered and recorded the track. Bieber immediately took to the beat and ended up freestyling what would become "Deja Vu" in the booth, with him and Malone going back and forth with ideas.

Bell and Malone were halfway through the latter's debut album, Stoney (2016), when they played him a track that producer Frank Dukes had done.

In an interview with Billboard, Malone's collaborator Louis Bell recalled that Bieber visited Malone in the studio in January 2016. Before collaborating on a song together, Post Malone opened for Justin Bieber on the Purpose World Tour, and the two developed a friendship.
