He played bass on a large number of well-known albums by ex-Beatles John Lennon, George Harrison and Ringo Starr − including All Things Must Pass, Imagine and The Concert for Bangladesh − and by artists such as Harry Nilsson, Doris Troy, Lou Reed, Gary Wright, Carly Simon and Randy Newman.

A Sideman's Journey is notable for including performances by Paul McCartney, Ringo Starr and Yusuf Islam (Cat Stevens), among others.

Three songs by his late friend George Harrison are included, as is a track Voormann co-wrote with soul singer Doris Troy for the latter's 1970 album on The Beatles' Apple label.

Paul McCartney sings and plays all instruments except bass guitar on the opening track, "I'm in Love Again", with additional drumming by Ringo Starr.

Ringo Starr plays drums on two of the tracks, but he declined an offer to sing his trademark song, "You're Sixteen"; Voormann instead selected a younger singer (Max Buskohl) to do the vocals, and to ensure that A Sideman's Journey would include musicians from all age groups.