For a few years after the Summer of Love, record stores were thick with hastily knocked-together concept albums about astrology or Indian mysticism or the occult, designed to cash in on the audience’s supposedly expanded consciousness. Here, it seemed, was another: a session musician reinventing himself as Dr John, singing songs about Louisiana voodoo thick with New Orleans slang and Creole patois, clad in a flamboyant Mardi Gras headdress and facepaint. Yet Gris Gris was anything but a novelty record. It was both one of the most extraordinary debut albums of the 60s and the beginning of a solo career that would last 51 years.

Its presentation certainly courted the psychedelic market – Dr John billed himself as the “Night Tripper”, a lysergic honorific that nodded to the Beatles – but the music bore almost no relation to anything else in rock music at the time. Instead, it boasted an innovative, brilliant and at times unsettling synthesis of New Orleans musical traditions – jazz, funk, rhythm and blues – made by a man steeped in both the city’s culture and the darker side of life. He certainly sounded like he knew of what he spoke: all the lyrics about serpent spirits and curses and witch doctors, which should have seemed like hokum, sounded authentically ominous and disturbing in Dr John’s coolly menacing drawl.

Mac Rebennack was nearing 30 when he transformed himself into Dr John and released Gris Gris: he had already packed a lifetime’s worth of musical experience and incident into his 27 years. His father’s connections as a record store owner in New Orleans’ Third Ward enabled him to sneak into local recording sessions: by 13, he was a professional musician, playing organ in strip clubs in the Third Quarter and performing with Professor Longhair, a local pioneer whose blend of blues, boogie-woogie and Afro-Cuban rhythms, Rebennack would later claim, “put the funk into music”.

Facebook Twitter Pinterest Sonic excess … Dr John at the New Orleans Jazz & Heritage festival, Louisiana in 2009. Photograph: Jim Mccarthy/Rex/Shutterstock

By 16, he was a session guitarist and occasional producer, working out of Cosimo Studios and playing in a succession of bands. He even had a local solo hit in 1959, a brooding Bo Diddley knock-off called Storm Warning, but Rebennack was also trouble: his career as a guitarist was ended when his finger was injured by a gunshot at a gig in Jackson in 1960; he became a heroin addict and dealer; he was involved in running a brothel. In 1963, he was sentenced to two years for drug offences, and on release shifted operations to Los Angeles, where a contingent of exiled New Orleans musicians – led by arranger Harold Battiste – were making headway as session players.

Rebennack became a member of the most revered Hollywood session group of all, the Wrecking Crew, playing with everyone from Sonny and Cher to Frank Zappa, but professed himself dissatisfied and homesick. Pining for New Orleans, he created the character of Dr John, loosely based on the legend of a 19th-century Senegalese freed slave turned New Orleans voodoo king, the music inspired by the disparate sounds Rebennack had heard at a spiritualist church in the Lower Ninth Ward. Here, he claimed, “Hindus and Buddhists, Jews, Christians, Masons, even voodoos” all worshipped together. He initially developed the idea for singer and actor Ronnie Barron, but when Barron balked, Rebennack took on the role, surrounding himself with fellow New Orleans expats and recording Gris Gris in late 1967.

The music Rebennack and Battiste concocted for the album was so out of step with prevalent trends that Atlantic Records boss Ahmet Ertegun initially refused to release it. In Rebennack’s retelling, Ertegun dismissed him as a “boogaloo motherfucker” when their paths crossed in the studio. But when it finally did come out, Gris Gris oddly chimed with the times. It sounded like it was recorded live, which clicked with the shift away from psychedelia to something more earthy and traditional, exemplified by the rootsy Americana of the Band’s Music from Big Pink, on release the same year.

Moreover, 1968 was the year that flower-power idealism curdled: it was a year of rioting, violence and upheaval, of Sympathy for the Devil rather than All You Need Is Love. That suited the album’s sinister atmosphere perfectly. Its flatly astonishing closer, I Walk on Gilded Splinters, offered up eight minutes of crawling malevolence and threatening braggadocio: if you took the title as a reference to needles, as plenty did, it sounded remarkably like a sneering, screw-you defence of Rebennack’s drug use, a distant Louisiana relation of the Velvet Underground’s Heroin. The live show Rebennack devised to support the album was a sensation, involving dancers wearing nothing but body paint, the singer disappearing in a puff of smoke and voodoo rituals. In St Louis, they were arrested after a band member bit the head off a chicken on stage.

If anything, Gris Gris’ followup, Babylon, was even further out: the lyrics more political and apocalyptic, the time signatures off-kilter, many of the instruments made by the eccentric inventor and composer Harry Partch. Rebenack and Battiste fell out after its recording, the latter protesting that his former collaborator was “a hopeless drug addict”. Certainly, Rebenack’s life seemed to be unravelling. During the making of 1970’s Remedies, he was committed to a psychiatric hospital, but escaped. Released unfinished, the album was as otherworldly and evil-sounding as ever, as demonstrated by the supremely disturbing 17-minute Angola Anthem. On arrival in London shortly after its release, Rebenack was feted by fans from the rock aristocracy, Mick Jagger and Eric Clapton among them, but recording sessions on which both featured descended into chaos – “everything was confusemental”, as Rebenack characteristically put it – and The Sun, Moon & Herbs was scythed from a projected triple album into a mere seven tracks.

Facebook Twitter Pinterest ‘He wore his elder-statesmen-of-the-Big-Easy status well’ ... Dr John. Photograph: Ian Dickson/Rex/Shutterstock

And yet Rebenack survived, even thrived. Pragmatically retiring the theatrical excesses and sonic weirdness of his Dr John persona, 1972’s Gumbo saw him charging masterfully through a selection of New Orleans R&B classics – Professor Longhair’s Tipitina among them – while its follow-up, In the Right Place (1973), pared him with funk band the Meters and legendary producer Allen Toussaint to striking effect: the album was his biggest US hit and the raw groove of Right Place, Wrong Time his biggest single.

It was a commercial peak he never scaled again. Desitively Bonnaroo attempted to repeat its predecessor’s formula with diminishing returns. Thereafter Rebenack’s albums became increasingly sporadic and variable in quality – 1979’s Tango Palace saw him unexpectedly, perhaps ill-advisedly, dabbling in disco – although he remained in demand as a sideman, working with everyone from Rickie Lee Jones to Van Morrison. He kicked drugs in 1989, and released In a Sentimental Mood. It wasa good album, his drawling vocals added real licentiousness to Makin’ Whoopee and a dissolute air to Accentuate the Positive, but a world away from Gris Gris and Babylon.

He was finally persuaded to don his Mardi Gras headdress once more by Jason Pierce of Spiritualized, on whose 1997 album Ladies and Gentlemen We Are Floating in Space Rebennack guested. The same year he released Anutha Zone, supported by a starry cast of younger British musicians – Supergrass, Paul Weller, the Beta Band, Martin Duffy of Primal Scream – all clearly in thrall to the Dr John myth and the strangeness of his first three albums. In truth, Anutha Zone never really matched the innovation or menace that characterised his earlier work; 2012’s Locked Down got him a lot closer, boasting a spacey, swampy production courtesy of the Black Keys’ Dan Auerbach and noticeably better songs, not least the fantastic Eleggua and Revolution.

But in his later years, Rebennack seemed more comfortable as a simpler artist or a kind of living reliquary of New Orleans musical practice, cutting tributes to Duke Ellington and Louis Armstrong, collections of Johnny Mercer standards and two strong albums inspired by the devastation wrought on his home town by Hurricane Katrina. He wore his elder-statesman-of-the-Big-Easy status well, genially pleading drug-related amnesia when asked by interviewers about the late 60s. (“I was tore down all that time … It’s hard for me to look back … It all falls into some grim abyss.”) But if he claimed not to remember it himself, it’s still likely to be the thing he’s best remembered for: not as the traditionalist he was at heart, but a visionary artist who took local traditions and transformed them into music that sounded like nothing else on Earth.

• This article was amended on 12 June 2019 to correct the spelling of the singer and actor Ronnie Barron’s name, from Barren as an earlier version said.