Lemmy was born in Stoke-on-Trent and grew up in Staffordshire and later North Wales. He was influenced by rock and roll and the early works of the Beatles, which led to him playing in several rock groups in the 1960s; including the Rockin' Vickers. He worked as a roadie for Jimi Hendrix and The Nice, before joining the space rock band Hawkwind in 1971, singing lead vocals on their hit "Silver Machine". After being fired from Hawkwind for drug possession in 1975, he founded Motörhead during the same year as the lead singer, Bassist, Songwriter and frontman. Motörhead's success peaked in 1980 and 1981 and included the hit single "Ace of Spades" and the top charting live album No Sleep 'til Hammersmith. Lemmy continued to record and tour regularly with Motörhead until his death in December 2015 in Los Angeles, where he had lived since 1990.

In Stockport, Lemmy joined local bands the Rainmakers and then the Motown Sect who played northern clubs for three years. In 1965, he joined the Rockin' Vickers who signed a deal with CBS, released three singles and toured Europe, reportedly being the first British band to visit the Socialist Federal Republic of Yugoslavia. The Rockin' Vickers moved to Manchester, where they shared a flat together. There, Lemmy got involved with a woman named Tracy who bore him a son, Paul Inder. Lemmy did not have any involvement in his life until the boy was six.

Leaving the Rockin' Vickers, Lemmy moved to London in 1967. He shared a flat with Noel Redding, Bassist of the Jimi Hendrix Experience, and with Neville Chesters, their manager. He got a job as a roadie for the band. In 1968, he joined the psychedelic rock band Sam Gopal under the name Ian Willis and recorded the album Escalator which was released in 1969. After meeting Simon King at a shopping centre in Chelsea in 1969, he joined the band Opal Butterfly; but the group soon disbanded, having failed to raise enough interest with their singles.

In August 1971, Lemmy joined the space rock band Hawkwind, who were based in Ladbroke Grove, London, as a Bassist and vocalist. He had no previous experience as a bass Guitarist, and was cajoled into joining immediately before a benefit gig in Notting Hill by bandmate Dik Mik to have two members who enjoyed amphetamines. He quickly developed a distinctive style that was strongly shaped by his early experience as a rhythm Guitarist, often using double stops and chords rather than the single note lines preferred by most bassists. His bass work was a fundamental part of the Hawkwind sound during his tenure, perhaps best documented on Space Ritual. He also provided the lead vocals on several songs, including the band's biggest UK chart single, "Silver Machine", which reached #3 in 1972.

In 1975, Lemmy was arrested at the Canada/United States border in Windsor, Ontario, on drug possession charges; he spent five days in jail but was released without charge. Nonetheless, he was fired from Hawkwind.

Lemmy made appearances in film and television, including the 1990 science fiction film Hardware and the 1987 comedy Eat the Rich, for which Motörhead also recorded the soundtracks including the title song. He appeared as himself in the 1986 The Comic Strip Presents... episode More Bad News, along with fellow heavy metal Musicians Ozzy Osbourne, the Scorpions and Def Leppard. In 1984, Motörhead were the musical guests on the TV show The Young Ones, in the episode "Bambi". He appears in the 1994 comedy Airheads (in which he is credited as "Lemmy von Motörhead"). Lemmy has a cameo in Ron Jeremy's 1994 pornographic film John Wayne Bobbitt Uncut as the discoverer of Bobbitt's severed penis. The appendage is thrown from the window of a moving car and lands at Lemmy's feet who exclaims: "Looks like a dick! Fucking hell! Ah well, it's not mine at least." The film's Soundtrack also features the Motörhead song "Under the Knife".

Lemmy worked with several Musicians, apart from his Motörhead bandmates, over the course of his career. He wrote the song "R.A.M.O.N.E.S" for the Ramones, which he played in his live sets as a tribute to the band. He was brought in as a Songwriter for Ozzy Osbourne's 1991 No More Tears album, providing lyrics for the tracks "Hellraiser," (which Motörhead later recorded themselves and released as a single), "Desire," "I Don't Want to Change the World" and the single "Mama I'm Coming Home". Lemmy noted in several magazine and television interviews that he made more money from the royalties of that one song than he had in his entire time with Motörhead. After being diagnosed with Type 2 diabetes in 2000, for which he was hospitalised briefly, Lemmy again appeared with Motörhead at WrestleMania X-Seven. Lemmy published his autobiography, White Line Fever, in November 2002. In 2005 Motörhead won their first Grammy in the Best Metal Performance category with their cover of Metallica's "Whiplash". In the same year he began recording an unreleased solo album titled Lemmy & Friends, which was intended to include a collaboration with Janet Jackson.

He was the main character in the 16-bit video game Motörhead, released for the Commodore Amiga and Atari ST in 1992. Lemmy provided his voice as the Arms Dealer in the 2006 game Scarface: The World Is Yours. Lemmy also appeared as an unlockable character in the 2009 game Guitar Hero: Metallica. He also provided his voice for the 2009 video game Brütal Legend, voicing the Kill Master, a character designed and based on his surname and likeness. Lemmy was also the inspiration for the Mario game character Lemmy Koopa, which made its first appearance in Super Mario Bros. 3.

Lemmy's first bass was a Hopf model that he bought soon after joining Hawkwind. For the majority of his career, he used Rickenbacker basses. In September 1996, his Rickenbacker bass was featured in the Bang Your Head exhibition at the Rock and Roll Hall of Fame in Cleveland, Ohio, US. Rickenbacker have introduced a signature 4004LK "Lemmy Kilmister" bass. He used a large, powerful, loud bass stack made by Marshall Amplification. Specifically, he used Marshall JMP Super Bass amplifier heads to drive three cabinets, each with four 15" speakers; the three heads were labelled "Killer," "No Remorse," and "Murder One". After he blew up "Murder One" he replaced it with a Marshall he named "Marsha". Early on he used perhaps his best known amp named "Hammer".

In 2005, the UK magazine Classic Rock presented Lemmy with its first "Living Legend" award. In a 2013 interview with the magazine, Lemmy said he had never expected to make it to 30, but he spoke very pointedly about the Future, indicating neither he nor the band were obsessing about the end:

The 2010 rockumentary film Lemmy was directed and produced by Greg Olliver and Wes Orshoski. It consists of a combination of 16 mm film and HD video footage, produced over three years. It features interviews with friends, peers, and admirers such as Dave Grohl, Slash, Ozzy Osbourne, James Hetfield, Lars Ulrich, Kirk Hammett, and Robert Trujillo of Metallica, David Ellefson of Megadeth, Scott Ian of Anthrax, Alice Cooper, Peter Hook of Joy Division/New Order, Dee Snider, Nikki Sixx, Mick Jones of the Clash, Ice-T, Kat Von D, Henry Rollins, Lars Frederiksen of Rancid, Jim Heath of The Reverend Horton Heat, Slim Jim Phantom of the Stray Cats, Mike Inez, Joan Jett, pro Skateboarder Geoff Rowley, pro Wrestler Triple H, "Fast" Eddie Clarke, Jarvis Cocker, Marky Ramone, former Hawkwind bandmates Dave Brock and Stacia, and Steve Vai.

Lemmy collected German military regalia; he had an Iron Cross encrusted on his bass, which led to accusations of Nazi sympathies. He stated that he collected the memorabilia because he liked the way it looked, and considered himself an anarchist or libertarian. Lemmy said he was against religion, government, and established authority. In 2011, he identified as agnostic, saying, "I can find out when I die. I can wait. I'm not in a hurry." Jeff Hanneman, the founder of the thrash metal band Slayer, befriended Lemmy due to their shared fondness for collecting Nazi memorabilia. According to Keith Emerson's autobiography, Lemmy gave him two of his Hitler Youth knives during his time as a roadie for the Nice. Emerson used these knives many times as keyholders when playing the Hammond organ during concerts with the Nice and Emerson, Lake & Palmer before destroying them. Lemmy defended his collection by saying that if his black girlfriend had no Problem with it, nobody else should.

Lemmy was well known for his alcohol abuse. The documentary Live Fast Die Old stated that he drank a bottle of Jack Daniel's every day and had done so since he was 30 years old. In 2013, Lemmy stopped drinking Jack Daniel's for health reasons. During his time with Hawkwind he developed an appetite for amphetamines and LSD, particularly the former. Before joining Hawkwind, he recalled Dik Mik, a former Hawkwind sound technician, visiting his squat in the middle of the night and taking speed with him. They became interested in how long "you could make the human body jump about without stopping", which they did for a few months, until Mik ran out of money and wanted to return to Hawkwind, taking Lemmy with him.

On 28 December 2015, four days after his 70th birthday, Lemmy died at his apartment in Los Angeles at 4pm PST, from prostate cancer, cardiac arrhythmia and congestive heart failure. Motörhead announced his death on their official Facebook page later that day. According to the band, his cancer had only been diagnosed two days prior to his death.

Lemmy's memorial Service took place at Forest Lawn Memorial Park, Hollywood Hills, on 9 January 2016. The Service was streamed live over YouTube with more than 230,000 people logging on to watch, while others gathered at the Rainbow. His body was cremated following the funeral. His remains were placed in a 3D-printed mantelpiece shaped like his trademark cavalry hat and emblazoned with the slogan "born to lose, lived to win". The piece was on display during his funeral and was later interred at Forest Lawn.

In February 2016, the Hollywood Vampires performed at the Grammy Award ceremony as a tribute to Lemmy. On 11 June, Download Festival paid tribute to Lemmy by renaming the main stage the "Lemmy Stage", and in the slot where Motorhead were due to play, there was a video tribute to Lemmy in which they played his music and his peers talked about him. On 17 November, Metallica released a tribute song titled "Murder One", named after Lemmy's frequently used amp. The song, from their album Hardwired... to Self-Destruct, depicts Lemmy's rise to fame. On 18 January 2017, Lemmy was inducted into the Hall of Heavy Metal History for being the creator of thrash metal. In 2017, the extinct crocodile-relative Lemmysuchus was named after Lemmy.