The Clash are mainly described as a punk rock band. According to Stephen Thomas Erlewine of AllMusic, "the Sex Pistols may have been the first British punk rock band, but the Clash were the definitive British punk rockers". Later in the band's career, the Clash started to use elements of many genres of music, including reggae, rockabilly, dub, and R&B. With their album London Calling, the band expanded their breadth of musical styles in the first double album of the "post-punk" period. The Clash's music has also been described as experimental rock and new wave.
In 2004, Rolling Stone ranked the Clash number 28 on its list of the 100 Greatest Artists of All Time, and in 2010, the band was ranked 22nd on VH1's 100 Greatest Artists of All Time. According to The Times, the Clash's debut, alongside Never Mind the Bollocks, Here's the Sex Pistols, is "punk's definitive statement" and London Calling "remains one of the most influential rock albums". In Rolling Stone's 2003 list of the 500 greatest albums of all time, London Calling ranked number 8, the highest entry by a punk band. The Clash was number 77 and Sandinista! was number 404. In the magazine's 2004 list of the 500 Greatest Songs of All Time, "London Calling" ranked number 15, again the highest for any song by a punk band. Four other Clash songs made the list: "Should I Stay Or Should I Go" (228), "Train in Vain" (292), "Complete Control" (361), and "White Man in Hammersmith Palais" (430). "London Calling" ranked number 48 in the magazine's 2008 list of the 100 Greatest Guitar Songs of All Time.
[T]he big watershed was the Clash album—that was go out, cut your hair, stop mucking about time, y'know. Up to that point we'd still been singing about bowling down California highways. I mean, it meant nothing to me. Although the Damned and the Pistols were great, they were only exciting musically; lyrically, I couldn't really make out a lot if it ... [T]o realise that [the Clash] were actually singing about their own lives in West London was like a bolt out of the blue.
The Clash also inspired many musicians who were only loosely associated, if at all, with punk. The band's embrace of ska, reggae and England's Jamaican subculture helped provide the impetus for the 2 Tone movement that emerged amid the fallout of the punk explosion. Other musicians who began performing while the Clash were active and acknowledged their debt to the band include Billy Bragg and Aztec Camera. U2's the Edge has compared the Clash's inspirational effect to that of the Ramones—both gave young rock musicians at large the "sense that the door of possibility had swung open." He wrote, "The Clash, more than any other group, kick-started a thousand garage bands across Ireland and the UK ... [S]eeing them perform was a life-changing experience." Bono has described the Clash as "the greatest rock band. They wrote the rule book for U2."
While the Sex Pistols’ debut gig at Manchester’s Lesser Free Trade Hall has been acknowledged as the starting point of that city’s punk scene, The Clash’s first gig at Eric’s, supported by The Specials, performed a similar magic for Liverpool. The gig was witnessed by Jayne Casey, Julian Cope, Pete Wylie, Pete Burns, Bill Drummond, Holly Johnson, Will Sergeant, Budgie, and Ian McCulloch, who went on to form Big in Japan, The Teardrop Explodes and Echo & The Bunnymen amongst other bands.
In later years, the Clash's influence can be heard in American political punk bands such as Rancid, Anti-Flag, Bad Religion, NOFX, Green Day, and Rise Against as well as in the political hard rock of early Manic Street Preachers. California's Rancid, in particular, are known as "incurable Clash zealots". The title track of the band's album Indestructible proclaims, "I'll keep listening to that great Joe Strummer!" Outside of rock music, Chuck D has credited the Clash as an inspiration for Public Enemy, in particular for the way their use of socially and politically conscious lyrics gained attention from the music press: "They talked about important subjects, so therefore journalists printed what they said, which was very pointed... We took that from the Clash, because we were very similar in that regard. Public Enemy just did it 10 years later". In 2019 Chuck D narrated Stay Free: The Story of The Clash, an eight-part podcast series produced by Spotify and BBC Studios.
According to biographer Antonio Ambrosio, The Clash's involvement with Jamaican musical and production styles has inspired similar cross-cultural efforts by bands such as Bad Brains, Massive Attack, 311, Sublime and No Doubt. Jakob Dylan of the Wallflowers lists London Calling as the record that "changed his life". Bands identified with the garage rock revival of the late 1990s and 2000s such as Sweden's the Hives, Australia's the Vines, Britain's the Libertines, and America's the White Stripes and the Strokes evince the Clash's influence. Among the many latter-day British acts identified as having been inspired by the Clash are Babyshambles, the Futureheads, the Charlatans, and Arctic Monkeys. Before M.I.A. had an international hit in 2008 with "Paper Planes", which is built around a sample from "Straight to Hell", she referenced "London Calling" on 2003's "Galang". A cover of "The Guns of Brixton" by German punk band Die Toten Hosen was released as a single in 2006. A version by reggae legend Jimmy Cliff with Tim Armstrong from Rancid was scheduled for release in November 2011. American-Irish punk band Dropkick Murphys released a cover of the song on Anti Heroes vs Dropkick Murphys in 1997.
In June 2009 Bruce Springsteen & the E Street Band opened their concert in Hyde Park, London, with 'London Calling'. The concert was later released on DVD as Bruce Springsteen and the E Street Band: London Calling – Live in Hyde Park. Bruce Springsteen, Little Steven, Dave Grohl and Elvis Costello performed the same song at the Grammysin 2003 as a tribute to Joe Strummer who died the year before. In 2009 Springsteen & the E Street Band even covered Strummer's "Coma Girl" while in 2014 and along with Tom Morello, they opened some of their shows on the High Hopes Tour with "Clampdown".
The band has also had a notable impact on music in the Spanish-speaking world. In 1997, a Clash tribute album featuring performances by Buenos Aires punk bands was released. Many rock en español bands such as Todos Tus Muertos, Café Tacuba, Maldita Vecindad, Los Prisioneros, Tijuana No, and Attaque 77 are indebted to the Clash. Argentina's Los Fabulosos Cadillacs covered "Should stay or should I go!", London Calling's "Revolution Rock" and "The Guns of Brixton" and invited Mick Jones to sing on their song "Mal Bicho". The Clash's influence is similarly reflected in Paris-founded Mano Negra's politicised lyrics and fusion of musical styles.
London Town a film in which tells the story of a Clash-obsessed teenager who crosses paths with Joe Strummer by happenstance in 1979 and finds his life changing as a result, was released in 2016. The film was met with mostly negative reviews and featured many timeline inaccuracies along with wrong song lyrics performed by the actors in the film.