Entwistle began his musical career playing brass instruments in Dixieland bands, which were very popular in England a few years prior to The Beatles and the British Invasion scene. He had been playing in a band called the Detours with a young, working-class guitarist named Roger Daltrey. Entwistle recommended another friend, Pete Townshend, as an extra guitarist for the group and, by 1964, with the addition of drummer Keith Moon, The Who's lineup was solidified.

Under the watchful eye of producer Shel Tamy (The Kinks) and managers Chris Stamp and Kit Lambert, The Who merged U.S. R&B with riff rock and British pop sensibilities. The result was an edgy new sound and rebellious songs like "My Generation,” and "Anyway, Anyhow, Anywhere (I Choose).”

John Entwistle had a much more creative role in The Who than he was ever given credit for. Although he was usually relegated to one or two songs per album, similar to George Harrison in The Beatles, those songs were always memorable, usually humorous, and provided a counterbalance to the serious introspection found in the compositions of Pete Townshend.