[2] To build anticipation for the song's release, the 1975 posted cryptic social media updates such as a typographic funnel composed of the title and the official lyric sheet.

It was officially released as a single on 18 October 2018, debuting as the Hottest Record on Annie Mac's self-titled BBC Radio 1 show.

[9] Dan Stubbs of NME called "It's Not Living (If It's Not with You)" a "Pretty in Pink [(1986)]-style power-pop banger that sings dreamily about heroin as if it were a great lost love".

[8] Pryour Stroud of Slant Magazine wrote that the song's opening guitar figure evokes an image of a fist thrust into a neon sky.

[16] Ross Horton of musicOMH called it "your favourite kind of 1975 track: plastic [1980s] pop you can see cropping up in any number of montages".

[17] The lyrics discuss using substance abuse as a coping mechanism for dealing with a failed relationship and unrequited love,[12] striking a parallel between heartbreak and addiction.

[15] In the pre-chorus, Healy sings about how the object of his affection will "collapse my veins wearing beautiful shoes", which Sasha Geffen of Pitchfork said creates an image of "a stiletto that's also a needle".

[19] Consequence of Sound writer David Sackllah classified it as a tragic love song that narrates the lure of addiction and Healy's struggle with heroin.

[23] Sackllah declared "It's Not Living (If It's Not with You)" as one of the album's three-best songs, praising its ability to incorporate a story about addiction "without glorifying it or sounding like a PSA".

[20] Horton felt the song is "clearly" the best track on A Brief Inquiry into Online Relationships, writing: "It sounds heavenly, like a couple of teenagers falling in love over a summer in Malibu in 1986.

[24] Geffen praised "It's Not Living (If It's Not with You)" for pairing dark lyrics with a bright production and upbeat chorus, calling the song the "tightest" single from A Brief Inquiry into Online Relationships while saying "Healy has all but perfected the art of making self-deprecation sound like a great time".

[8] Richards praised it for being both an intimate personal account and a relatable, transferable statement, and noted that the song helps provide the anchor to the overall album.

[6] In a mixed review, Chris Conaton of PopMatters praised the songwriting but felt "It's Not Living (If It's Not with You)" is not fresh or interesting, opining that the song is "such a dead-on '80s synth-rock track that it suffers in comparison to actual '80s hits like Simple Minds' 'Don't You (Forget About Me)' [(1985)]".

[27] Pitchfork ranked the song at number 60 on their year-end list, calling it a dark meditation on drug use and a "ruthlessly efficient pop [machine]".

[15] NME declared the track the 30th-best song of 2018, with Rhian Daly calling it a melodic dream while saying the line "collapse my veins wearing beautiful shoes" is one of the most stunning lyrics about drug consumption ever written.

[28] The publication also deemed "It's Not Living (If It's Not with You)" the eighth-best song of the band's career, with TC saying the track "takes what ought to be a tough listen and spins it into a miraculous rebirth".

[29] Stereogum ranked it at number 14 on their 2018 year-end list; Chris DeVille praised the song's revisionist nostalgia and "brand of [1980s] adult contemporary ultracheese".

He said the visual is preternaturally dark, calling it a brilliant homage to Stop Making Sense that metaphorically represents the difficulties of Healy's struggle with heroin withdrawal.

[46] Winston Cook-Wilson of Spin called the video a hallucinatory tribute to Stop Making Sense and compared it to Black Mirror, saying: "Perhaps Charlie Brooker should get in touch.

[45] Shahlin Graves of Coup de Main said the music video is excellent and specifically praised Adam Hann's performance.