John Kahn always wanted to be a musician. He took piano lessons when he was a boy, and over the years learned to play many instruments, including the piano, bass guitar, and guitar. He went to college (University of Southern California) and attended the San Francisco Conservatory of Music intending to become a composer, but didn't complete either course of study. He did, however become a very successful studio musician and played with some well known bands.

Kahn first met and began playing music with Jerry Garcia in the late 1960s when they both were regulars at a Monday night jam session at a club called the Matrix in San Francisco. Jerry Garcia, Howard Wales, Kahn, and Bill Vitt, who was the drummer for the Bloomfield Band at the time would meet and jam to an empty house, as there were usually few if any people in the audience. Popularity grew, however, and Wales decided he didn't want to perform with the group any longer. That's when Merle Saunders joined the new group, and the Jerry Garcia Band was born.

Kahn was doing a lot of studio work during this time as well, performing regularly with Mike Bloomfield, Paul Butterfield Band, Otis Rush and John Lee Hoooker. Around 1973 Jerry Garcia, Peter Rowan and David Grisman started up a band called Old and In the Way, a bluegrass band. They needed a bass player and asked Kahn to join. He accepted and played with that band as well. Kahn appeared on over 60 albums over the years with many different artists. He died peacefully in his home in Marin, California in 1996.