Music journalist  said 's "journey" to making All Things Must Pass started when he visited America in late 1968, after the acrimonious sessions for '  (also known as the "White Album"). At  in November, Harrison started a long-lasting friendship with  and experienced a creative equality with  that contrasted with  and 's dominance in the Beatles. He also wrote more songs, renewing his interest in the guitar after three years studying the Indian . As well as being one of the few musicians to co-write songs with Dylan, Harrison had recently collaborated with  on "", which became a hit single for  in the spring of 1969.

Once back in London, and with his compositions continually overlooked for inclusion on releases by the Beatles, Harrison found creative fulfilment in extracurricular projects that, in the words of his musical biographer, Simon Leng, served as an "emancipating force" from the restrictions imposed on him in the band. His activities during 1969 included producing  signings  and , two American singer-songwriters whose  and  roots proved as influential on All Things Must Pass as the music of the Band. He also recorded with artists such as  and , and accompanied Clapton on a short tour with 's soul revue, . In addition, Harrison identified his involvement with the  as providing "another piece of a jigsaw puzzle" that represented the spiritual journey he had begun in 1966. As well as embracing the  branch of , Harrison produced two hit singles during 1969–70 by the UK-based devotees, credited as . In January 1970, Harrison invited American producer  to participate in the recording of Lennon's  single "" This association led to Spector being given the task of salvaging the Beatles'  rehearsal tapes, released officially as the  album (1970), and later co-producing All Things Must Pass.

Harrison first discussed the possibility of making a solo album of his unused songs during the ill-tempered Get Back sessions, held at  in January 1969. On 25 February, his 26th birthday, Harrison recorded  of "" and two other compositions that had received little interest from Lennon and McCartney at Twickenham. With the inclusion of one of these songs – "" – and "" on the Beatles'  album in September 1969, music critics acknowledged that Harrison had bloomed into a songwriter to match Lennon and McCartney. He began talking publicly about recording his own album from the autumn of 1969, but only committed to the idea after McCartney announced that he was leaving the Beatles in April 1970. Included as part of the promotional material for McCartney's , this announcement signalled . Despite having already made  (1968), a mostly instrumental soundtrack album, and the experimental  (1969), Harrison considered All Things Must Pass to be his first solo album.

I went to George's Friar Park ... and he said, "I have a few ditties for you to hear." It was endless! He had literally hundreds of songs and each one was better than the rest. He had all this emotion built up when it was released to me.

– Phil Spector, on first hearing Harrison's backlog of songs in early 1970

Spector first heard Harrison's stockpile of unreleased songs early in 1970, when visiting his recently purchased home, . "It was endless!" Spector later recalled of the recital, noting the quantity and quality of Harrison's material. Harrison had accumulated songs from as far back as 1966; both "" and "" date from that year. He co-wrote at least two songs with Dylan while in Woodstock, one of which, "", appeared as the lead track on All Things Must Pass. Harrison also wrote "" in late 1968.

He introduced the Band-inspired "All Things Must Pass", along with "" and "Let It Down", at the Beatles' Get Back rehearsals, only to have them rejected by Lennon and McCartney. The tense atmosphere at Twickenham fuelled another All Things Must Pass song, "", which Harrison wrote in the wake of his temporary departure from the band on 10 January 1969. Harrison later confirmed that the song was a "swipe" at McCartney. "" followed soon afterwards, its lyrics focusing on the failure of friendships within the Beatles amid the business problems surrounding their . Harrison's musical activities outside the band during 1969 inspired other songs on the album: "" came to him while driving to a London session that spring for Preston's  album; "" was Harrison's message of encouragement to Dylan, written the night before the latter's comeback performance at the ; and Harrison began "" as an exercise in writing a gospel song during Delaney & Bonnie's stopover in Copenhagen in December 1969.

"" resulted from Harrison's early experiments with , a technique to which Bramlett had introduced him, in order to cover for guitarist 's departure from the Friends line-up. Other songs on All Things Must Pass, all written during the first half of 1970, include "", which reflected Harrison's adoption of chanting through his involvement with the Hare Krishna movement; "", a tribute to the original owner of Friar Park; and "". The latter was another song influenced by Harrison's association with the Radha Krishna Temple, and was written while some of the devotees were staying with him at Friar Park.

On 1 May 1970, shortly before beginning work on All Things Must Pass, Harrison attended a Dylan session in New York, during which he acquired a new song of Dylan's, "". Harrison wrote "", which was one of a number of Dylan-influenced songs on the album, towards the end of production on All Things Must Pass, as a tribute to the  who had kept a vigil outside the studios where he was working.

According to Leng, All Things Must Pass represents the completion of Harrison's "musical-philosophical circle", in which his 1966–68 immersion in Indian music found a Western equivalent in gospel music. While identifying ,  and  among the other genres on the album, Leng writes of the "plethora of new sounds and influences" that Harrison had absorbed through 1969 and now incorporated, including "Krishna chants, gospel ecstasy, Southern blues-rock [and] slide guitar". The melodies of "Isn't It a Pity" and "Beware of Darkness" have aspects of , and on "My Sweet Lord", Harrison combined the Hindu  tradition with gospel. Rob Mitchum of  describes the album as "dark-tinged Krishna folk-rock".

The recurrent lyrical themes are Harrison's spiritual quest, as it would be throughout his solo career, and friendship, particularly the failure of relationships among the Beatles. Music journalist  says that Harrison sings of "deep love – for his faith, for life and the people around him". He adds that the songs are performed with "tension and urgency" as if "the whole thing is happening on the edge of a canyon, an abyss into which the '60s is about to topple".

On the original 's third disc, titled , four of the five tracks – "Out of the Blue", "Plug Me In", "I Remember Jeep" and "Thanks for the Pepperoni" – are improvised  built around minimal  changes, or in the case of "Out of the Blue", a single-chord . The title for "I Remember Jeep" originated from the name of Clapton's dog, Jeep, and "Thanks for the Pepperoni" came from a line on a  comedy album. In a December 2000 interview with  magazine, Harrison explained: "For the jams, I didn't want to just throw [them] in the cupboard, and yet at the same time it wasn't part of the record; that's why I put it on a separate label to go in the package as a kind of bonus."

The only vocal selection on Apple Jam is "It's Johnny's Birthday", sung to the tune of 's 1968 hit "", and recorded as a gift from Harrison to Lennon to mark the latter's 30th birthday. Like all the "free" tracks on the bonus disc, "It's Johnny's Birthday" carried a Harrison songwriting credit on the original UK release of All Things Must Pass, while on the first US copies, the only songwriting information on the record's face labels was the standard inclusion of a performing rights organisation, . In December 1970, "Congratulations" songwriters  and  claimed royalties, with the result that the composer's credit for Harrison's track was swiftly changed to acknowledge Martin and Coulter.

The precise line-up of contributing musicians is open to conjecture. Due to the album's big sound and the many participants on the sessions, commentators have traditionally referred to the grand, orchestral nature of this line-up. In 2002, music critic  described it as "a who's who of the decade's rock royalty", while Harris writes of the cast taking on "a  aspect".

The musicians included , , , ,  and Dave Mason, all of whom had recently toured with Delaney & Bonnie. Along with Eric Clapton, there were also musicians whose link with Harrison went back some years, such as Ringo Starr, Billy Preston and German bassist , the latter formerly of  and a friend since the Beatles' . Handling much of the keyboard work with Whitlock was , who went on to collaborate regularly with Harrison throughout the 1970s.

That was the great thing about [the Beatles] splitting up: to be able to go off and make my own record ... And also to be able to record with all these new people, which was like a breath of fresh air.

– George Harrison, December 2000

From within Apple's stable of musicians, Harrison recruited the band , future  drummer , and Beatles assistant  on percussion. Badfinger drummer ' powerful tambourine work led to Spector giving him the nickname "Mr Tambourine Man", after the . According to Gibbins, he and White played most of the percussion parts on the album, "switch[ing] on tambourine, sticks, , maracas ... whatever was needed". Gibbins' bandmates ,  and  provided rhythm acoustic-guitar parts that, in keeping with Spector's  principles, were to be "felt but not heard". Other contributors included 's , on keyboards, and  player , the last of whom Harrison flew over from Nashville for a few days of recording.

Adding to his and Badfinger's acoustic guitars on some All Things Must Pass tracks, Harrison invited  to the sessions. Although uncredited for his contributions, Frampton also played acoustic guitar on the country tracks featuring Drake; he and Harrison later overdubbed further rhythm parts on several songs. Orchestral arranger  also attended the sessions, occasionally contributing on  and . Simon Leng consulted Voormann, Barham and Molland for his chapter covering the making of All Things Must Pass and credits  as one of the keyboard players on both versions of "Isn't It a Pity". , Clapton's former bandmate in Cream and , played drums on the jam track "I Remember Jeep".

For contractual reasons, on UK pressings of All Things Must Pass, Clapton's participation on the first two discs remained unacknowledged for many years, although he was listed among the musicians appearing on the Apple Jam disc. A pre-  played  at a session for "Art of Dying". Harrison gave him a credit on the 30th anniversary reissue of the album, but Collins' playing does not appear on the track. Unsubstantiated claims exist regarding guest appearances by John Lennon,  and 's . In addition, for some years after the album's release, rumours claimed that the Band backed Harrison on the country-influenced "Behind That Locked Door".

You could feel after the first few sessions that it was going to be a great album.

– Klaus Voormann, 2003

Music historian  comments that, typical of the Beatles' solo work, the precise dates for the recording of All Things Must Pass are uncertain, a situation that contrasts with the "meticulous documentation" available for the band's studio activities. According to a contemporaneous report in , pre-production began on 20 May 1970, the same day as the  film's world premiere. Authors Chip Madinger and Mark Easter cite this as the probable date for Harrison's run-through of songs for Spector. , who worked as an   in 1970, recalled that the sessions were preceded by a week of Harrison recording demos, accompanied by Starr and Voormann. The first formal recording session for the album took place at EMI Studios (now ) on 26 May, although Unterberger states that "much or all" of that day's recording was not used.

The majority of the album's backing tracks were taped on  at EMI between late May and the second week of June. The recording engineer was , with Leckie as his tape operator. Spector recorded most of the backing tracks live, in some cases featuring multiple drummers and keyboard players, and as many as five rhythm guitarists. In Whitlock's description, the studio space was a "massive room ... two sets of drums on risers, a piano, organ and other keyboards to the wall on the left, up against the far wall on the right were Badfinger, and in the centre were George and Eric and the guitars". Molland recalled that, to achieve the resonant acoustic guitar sound on songs such as "My Sweet Lord", he and his bandmates were partitioned off inside a plywood structure.

According to Voormann, Harrison set up a small altar containing figurines and burning incense, creating an atmosphere in which "everyone felt good." Having suffered in the Beatles at McCartney's tendency to dictate how each musician should play, Harrison allowed the contributors the freedom to express themselves in their playing. All the participants later recalled the project favourably.

The first song recorded was "Wah-Wah". During the playback, Harrison was shocked at the amount of echo Spector had added, since the performance had sounded relatively dry through the musicians' headphones. Voormann immediately "loved" the sound, as did Clapton; Harrison later said: "I grew to like it."

"What Is Life", versions one and two of "Isn't It a Pity", and the songs on which Drake participated, such as "All Things Must Pass" and "Ballad of Sir Frankie Crisp", were among the other tracks taped then. Preston recalled that Spector's approach was to have several keyboards playing the same chords in different , to strengthen the sound. Preston said he had reservations about this approach but "with George's stuff it was perfect." According to White, a "really good bond" formed among the musicians; the main sessions lasted three weeks and "There was no mucking around." Badfinger participated in five sessions until early June, when they left for an engagement in Hawaii. Molland said they would record two or three songs each day, and that Harrison ran the sessions, rather than Spector. Wright recalls that as the project progressed, the large cast of musicians was pared down. He says that the later recording sessions featured a core group of himself, Harrison, Clapton, Starr or Gordon on drums, and Voormann or Radle playing bass.

The Apple Jam instrumentals "Thanks for the Pepperoni" and "Plug Me In", featuring Harrison, Clapton and Mason each taking extended guitar solos, were recorded later in June, at the Beatles' , and marked the formation of Clapton, Whitlock, Radle and Gordon's short-lived band . Harrison also contributed on guitar to both sides of the band's debut single, "" and "Roll It Over", which were produced by Spector and recorded at Apple on 18 June. The eleven-minute "Out of the Blue" featured contributions from Keys and Price, both of whom began working with  around this time. According to Keys in his autobiography Every Night's a Saturday Night, he and Price added their horns parts to songs such as "What Is Life" after the backing tracks had been recorded. He recalls that Harrison and Price worked out the album's horn arrangements together in the studio.

In his 2010 autobiography, Whitlock describes the All Things Must Pass sessions as "spectacular in every way", although he says that the project was informed by Harrison's preoccupation with his former bandmates and ongoing difficulties with Klein and Apple. Wright recalls Harrison's discomfort when Lennon and  visited the studio, saying: "His vibe was icy as he bluntly remarked, 'What are you doing here?' It was a very tense moment ..." According to Whitlock, Harrison played the couple some of his new music and Lennon "got his socks blown off", much to Harrison's satisfaction. The presence of Harrison's friends from the Radha Krishna Temple caused disruption during the sessions, according to Gibbins and Whitlock. While echoing this view, Spector cited this as an example of how Harrison inspired tolerance, since the Temple devotees could be "the biggest pain in the necks in the world" yet Harrison "was spiritual and you knew it", which "made you like those Krishnas".

Although Harrison had estimated in a New York radio interview that the solo album would take no more than eight weeks to complete, recording,  and mixing on All Things Must Pass lasted for five months, until late October. Part of the reason for this was Harrison's need to make regular visits to Liverpool to tend to his mother, who had been diagnosed with cancer. Spector's erratic behaviour during the sessions was another factor affecting progress on the album. Harrison later referred to Spector needing "eighteen " before he could start work, a situation that forced much of the production duties onto Harrison alone. At one point, Spector fell over in the studio and broke his arm. He subsequently withdrew from the project due to what Madinger and Easter term "health reasons".

Early in July, work on All Things Must Pass was temporarily brought to a halt as Harrison headed north to see his dying mother for the last time. EMI's growing concerns regarding studio costs added to the pressure on Harrison. A further complication, according to Harris, was that Clapton had become infatuated with Harrison's wife, , and adopted a  habit as a means of coping with his guilt.

In Spector's absence, Harrison completed the album's backing tracks and carried out preliminary overdubs, doing much of the latter work at  with former Beatles engineer . Harrison completed this stage of the project on 12 August. He then sent early mixes of many of the songs to his co-producer, who was convalescing in Los Angeles, and Spector replied by letter dated 19 August with suggestions for further overdubs and final mixing. Among Spector's comments were detailed suggestions regarding "Let It Down", the released recording of which Madinger and Easter describe as "the best example of Spector running rampant with the 'Wall of Sound'", and an urging that he and Harrison carry out further work on the songs at Trident because of its  recording desk. Spector also made suggestions about overdubbing more instruments and orchestration on some tracks, but encouraged Harrison to focus on his vocals and avoid hiding his voice behind the instrumentation.

John Barham's orchestrations were recorded during the next phase of the album's production, starting in early September, along with many further contributions from Harrison, such as his lead vocals, slide guitar parts and multi-tracked backing vocals (the latter credited to "the George O'Hara-Smith Singers"). Barham stayed at Friar Park and created the music scores from melodies that Harrison sang or played to him on piano or guitar. Leng recognises the arrangements on "pivotal" songs such as "Isn't It a Pity", "My Sweet Lord", "Beware of Darkness" and "All Things Must Pass" as important elements of the album's sound.

According to Scott, he and Harrison worked alone for "weeks and months" on the overdubs, as Harrison recorded the backing vocals and lead guitar parts. In some cases, they slowed the tape down to allow Harrison to sing the high-register vocal lines. Spector returned to London for the later mixing stage. Scott says that Spector would visit Trident for a few hours and make suggestions on their latest mixes, and that some of Spector's suggestions were followed, others not.

Spector has praised Harrison's guitar and vocal work on the overdubs, saying: "Perfectionist is not the right word. Anyone can be a perfectionist. He was beyond that ..." Harrison's approach to slide guitar incorporated aspects of both Indian music and the  tradition; he developed a precise playing style and sound that partly evoked the fretless Indian . From its introduction on All Things Must Pass, Leng writes, Harrison's slide guitar became his musical signature – "as instantly recognisable as Dylan's harmonica or 's".

If I were doing [All Things Must Pass] now, it would not be so produced. But it was the first record ... And anybody who's familiar with Phil [Spector]'s work – it was like  sound.

– George Harrison, January 2001

On 9 October, while carrying out final mixing at EMI, Harrison presented Lennon with the recently recorded "It's Johnny's Birthday". The track featured Harrison on vocals, harmonium and all other instruments, and vocal contributions from Mal Evans and assistant engineer Eddie Klein. That same month, Harrison finished his production work on Starr's 1971 single "", the basic track for which they had recorded with Voormann in March at Trident. Aside from his contributions to projects by Starr, Clapton, Preston and Ashton during 1970, over the following year Harrison would reciprocate the help that his fellow musicians on All Things Must Pass had given him by contributing to albums by Whitlock, Wright, Badfinger and Keys.

On 28 October, Harrison and Boyd arrived in New York, where he and Spector carried out final preparation for the album's release, such as sequencing. Harrison harboured doubts about whether all the songs they had finished were worthy of inclusion. Allan Steckler, Apple Records' US manager, was "stunned" by the quality of the material and assured Harrison that he should issue all the songs.

Spector's signature production style gave All Things Must Pass a heavy, -oriented sound, which Harrison came to regret. Whitlock says that, typical of Spector's Wall of Sound, there was some reverb on the original recordings but the effect was mostly added later. In music journalist 's description, once abandoned by his co-producer midway through the summer, Harrison had "proceeded to out-Spector Spector" through the addition of further echo and multiple overdubs. Voormann has said that Harrison "cluttered" the album's sound in this way, and "admitted later that he put too much stuff on top". According to Leckie, however, the reverb on tracks such as "My Sweet Lord" and "Wah-Wah" was recorded onto tape at the time, because Spector insisted on hearing the effects in place as they worked on the tracks. Outtakes from the recording sessions became available on bootlegs in the 1990s. One such unofficial release, the three-disc The Making of All Things Must Pass, contains multiple takes of some of the songs on the album, providing a work-in-progress on the sequence of overdubs onto the backing tracks.