Lemmy spent the sixties in a number of small-time bands including Opal Butterfly, Sam Gopal, and The Rockin' Vickers as well as working as a roadie for Jimi Hendrix in 1967 for about six months, and as a roadie for The Nice. In 1971 he joined archetypal space rock UK Underground outfit Hawkwind who were centred around the very in Ladbroke Grove. His distinctive style of bass playing, involving the use of chords rather than the single notes preferred by most players, was a fundamental part of the Hawkwind sound during his tenure. He also provided lead vocals on a number of songs including the band's biggest UK chart single, Silver Machine, which reached No.3 in 1972.

By 1975 Lemmy's forceful personality and propensity for ingesting copious quantities of amphetamines were leading to conflict with other members, and this culminated with his sacking after being arrested for drug possession while on tour with the band in Canada. Lemmy went on to form a new band with guitarist Larry Wallis and drummer Lucas Fox. Wallis's former bands included the Pink Fairies, Steve Took's Shagrat and UFO. Lemmy's connection with Took (formerly of T Rex) was not limited to Wallis, as they were personal friends and Took was the step-father to Lemmy's son Paul. This new band was originally called Bastard. However, after the band's manager pointed out this name would lose them TV and radio exposure, it was changed to Motörhead - the last song Lemmy wrote for Hawkwind.

After a short period both Wallis and Fox were replaced with guitarist "Fast" Eddie Clarke and drummer Phil "Philthy Animal" Taylor, and with this line-up the band began to achieve success. The uncompromisingly intense nature of their sound appealed to both Lemmy's original metal/rock constituency as well as the new punk fans — intrigued, perhaps, by Lemmy's brief stint in The Damned — and Lemmy's guttural vocals were unique in the world of rock at that time. The band's success peaked between 1980 and 1981 with a number of UK chart hits, including the classic single Ace of Spades (still a crowd favourite today) and the No. 1 Live Album No Sleep 'til Hammersmith . Motörhead have since gone on to become one of the most influential bands on the heavy metal scene and, although Lemmy is the only constant in a changing line-up, are still performing and releasing records to this day. Despite Motorhead's many member changes over their 30 year history the current lineup of Lemmy, Phil Campbell and Mikkey Dee has remained constant since 1995.

Lemmy has also worked with a number of other musicians over his career, and occasionally guests with Hawkwind. He was brought in as a songwriter for Ozzy Osbourne's 1991 No More Tears album, providing lyrics for the tracks "Hellraiser," (which Motorhead later released) "Desire," "I Don't Want To Change The World," and the massive hit "Mama I'm Coming Home." Lemmy has 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 Motorhead.

He has made a number of 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. In the 1994 comedy Airheads (in which he is credited as "Lemmy von Motorhead"), he shouts (truthfully) about being the editor of his high school newspaper. He has also appeared in several movies from the Troma studio. Having a predilection for self-deprecating parody, he once appeared in an advertisement for Kit Kat chocolate bars, miming a piece of chamber music on the violin, in an upper-class tea-room. Motörhead performed the entrance theme song "The Game" for World Wrestling Entertainment (WWE)'s Triple H, as well as "Line in the Sand" for his now defunct wrestling stable, Evolution. In 2006, they once again provided theme music for the WWE as they recorded the song King of Kings for Triple H on the Wreckless Intent CD.

Lemmy collects Nazi memorabilia, and has an Iron Cross encrusted on his bass, which has led to accusations of right-wing extremist tendencies; however, Lemmy considers himself to be an anarchist. According to Keith Emerson as written in his autobiography, two of Lemmy's Hitlerjugend knives were gifted to Keith Emerson himself during Lemmy's time spent as a roadie for The Nice. Emerson used these knives many times as "keyholders" during his famous wrestling sessions with the Hammond Organ during the shows with The Nice and Emerson, Lake & Palmer.

He published his autobiography, White Line Fever in November 2002.