John Lee Clayton Jr. was born August 20, 1952, in Venice, California, and began on bass in elementary school, playing in strings class, junior orchestra, high school jazz band and orchestra, and soul/R&B groups. In 1969, at sixteen, he enrolled in bassist Ray Brown's jazz class at UCLA, whose own career is covered in full in his JazzProfiles.com profile, beginning a close relationship that lasted more than three decades and became his most influential musical education. He completed his studies at Indiana University in 1975 with a Bachelor of Music in Double Bass.

After graduating, Clayton toured with the Monty Alexander Trio (1975-1977) and the Count Basie Orchestra (1977-1979), then settled as principal bassist with the Amsterdam Philharmonic Orchestra in the Netherlands (1980-1985). In 1985 he co-founded the Clayton-Hamilton Jazz Orchestra with his brother, saxophonist Jeff Clayton, and drummer Jeff Hamilton, whose own career is covered in full in his JazzProfiles.com profile; the trio also formed the Clayton Brothers. John and Jeff Clayton are the father and uncle, respectively, of pianist Gerald Clayton.

A seven-time Grammy-nominated bassist, composer, arranger, and conductor, Clayton's talents are consistently requested by figures including Quincy Jones and Tommy LiPuma. He has written and arranged music for Diana Krall, Dee Dee Bridgewater, whose own career is covered in full in her JazzProfiles.com profile, including her Grammy-winning album Dear Ella, Natalie Cole, Milt Jackson, Nancy Wilson, Quincy Jones, George Benson, Dr. John, Gladys Knight, Regina Carter, and Queen Latifah.

Clayton's more than three decades of mentorship under Ray Brown, combined with his parallel careers as bassist, arranger, and conductor, made him one of the most versatile and widely requested figures in mainstream jazz, and his Clayton-Hamilton Jazz Orchestra continues one of the strongest big-band traditions of the post-swing era.