"How to Disappear Completely" was later included on the special edition of Radiohead: The Best Of (2008) and reissued on Kid A Mnesia (2021), which also featured the song's isolated string track.

"[17] In an interview with Terry David Mulligan in Canada in July 1997, Yorke mentioned he had written a song the previous month with the chorus: "I'm not here / This isn't happening.

[26] In a 1998 review, Melody Maker likened one rendition to Radiohead covering Unbelievable Truth,[27] an acoustic band led by Yorke's younger brother, Andy.

[32] According to some accounts, the song was dedicated to Manic Street Preachers' guitarist Richey Edwards,[33][34] who disappeared in February 1995 and was declared dead in November 2008.

[43] On 1 December 1999, Radiohead recorded Philip Selway's drum parts in preparation for a collaboration with the Orchestra of St John's,[40] which they chose due to its performances of works by composers Krzysztof Penderecki and Olivier Messiaen.

[30] On 2 December 1999,[40] with the assistance of producer Nigel Godrich,[5] Greenwood, the only band member formally trained in music theory,[48] began composing the string arrangement.

[57] "How to Disappear Completely" is an acoustic-driven ballad, underpinned by "forlorn" strings and "compelling" guitar effects,[58][4] incorporating elements of orchestral and ambient music.

[61][65] Ryan Pinkard of Tidal Magazine referred to it as a "majestic" pop ballad,[66] while Jazz Monroe of The Guardian categorised it as avant-garde balladry, describing it as a "masterpiece" that "orchestrates a stage-fright reverie with fragments of Robert Wyatt and Penderecki".

[67] Stephen Dalton of Uncut called it a "sumptuous" orchestral ballad,[68] whereas Steve Lowe of Q magazine characterised it as a "ghostly waltz-time" folk song, influenced by the Smiths' album Meat Is Murder (1985).

[70] It features strummed acoustic guitar,[71] a Chris Squire-influenced bassline,[72] and a foundation of strings that evolves into "paranoid" electronica and "lush" orchestration,[71] drawing influence from the Moody Blues.

[49] Jamie Kahn of Far Out praised the strings for blending seamlessly with the acoustic guitar and Yorke's "haunting" vocals, creating an "eclectic, harmonious" composition.

"[84] The lyrics are poetic and referential, resisting literal interpretation, as seen in the lines: "Strobe lights and blown speakers / Fireworks and hurricanes / I'm not here / This isn't happening".

[85] James Oldham of NME wrote that the chorus, "I'm not here / This isn't happening", encapsulates Yorke's mental state and the overwhelming pressures that he and the rest of the band endured during the OK Computer tour.

[94][95] A live audio version, recorded on 15 November 2000 for BBC Radio 1's Evening Session,[96] was included on the Kid A "Special Collectors Edition" reissue in 2009.

[99] The show's music supervisor, Alexandra Patsavas, recalled: Jason Katims and Ron Moore were keen to get the track for an episode, but Radiohead for television—even great television—seemed so out of reach.

[103] In a 2000 article published prior to the release of Kid A, Melody Maker's Andre Paine described "How to Disappear Completely" as "several minutes of music that sounds like the Smiths produced by DJ Shadow".

[104] Reviewing Kid A in 2000, NME's Keith Cameron noted that the song marked Radiohead's "return to the big ballad template, as massed strings swoon and Yorke's voice soars transcendentally for the first time".

[105] Rolling Stone critic David Fricke wrote that the song "moves like an ice floe: cold-blue folk rock with just a faint hint of heartbeat.

"[106] Brent DiCrescenzo of Pitchfork stated that the song "boil[ed] down [OK Computer tracks] 'Let Down' and 'Karma Police' to their spectral essence", claiming it "comes closest to bridging Yorke's lyrical sentiment to the instrumental effect.

"[63] Billboard described "How to Disappear Completely" as "haunting", noting that "vocalist Thom Yorke is as tortured as ever, proclaiming 'I'm not here/This isn't happening' [...] as if he'd already vanished long ago.

[108] Simon Reynolds of Uncut described the song as a "missing link" between Scott Walker's orchestral compositions and the "swoonily amorphous" ballads on My Bloody Valentine's album Isn't Anything (1988).

[79] He also drew comparisons between its acoustic guitar, which "slowly builds to an operatic emotional climax", and earlier Radiohead songs such as "Fake Plastic Trees" and "Exit Music".