Having played with Brian Auger's Oblivion Express, appearing on the band's first three albums together with future Average White Band drummer Robbie McIntosh, Jim Mullen then joined Kokomo and later toured with the Average White Band.
It was while both musicians were touring the US with AWB in the mid-70s that Mullen met up with tenor saxophone player Dick Morrissey, and throughout the 1980s, he found considerable critical acclaim as joint leader of the pioneering British jazz funk band Morrissey-Mullen. Record producer Richard Niles, who produced the band's sixth album, It's About Time, would go on to produce three solo albums for Mullen.
Mullen has also played and recorded with, among others, Mose Allison, Hamish Stuart Jimmy Witherspoon, and Georgie Fame. He has won many British music awards including 'Best Guitar' in the British Telecom Jazz Awards (1994, 1996 and 2000). Most recently, Jim Mullen has recorded as part of The All Stars a collective of session musicians on their Paul McCartney-produced album All About the Music, alongside special guests Jocelyn Brown, Hamish Stuart and Angelo Starr.