Born in Liverpool to a father of Swedish descent and mother of Irish descent,^[2] he is known for his work with 1960s bands The Big Three and The Merseybeats, and for singing on the original recording of Jesus Christ Superstar as Simon Zealotes. He made an appearance on Roger Glover's The Butterfly Ball and the Grasshopper's Feast album track, "Watch Out for the Bat", as a vocalist. He is probably best known for playing bass guitar for several re-incarnations of the Ian Gillan Band and for his earlier participation in the progressive rock band, Quatermass. He also re-formed The Pirates, originally the backing band for Johnny Kidd.^[3]

Gustafson performed on three studio albums for Roxy Music during the years of 1973 through 1975. However, he was frequently not with the band on live dates, often being replaced by John Wetton or Sal Maida. His final record with the band, Siren, included their only American top 40 hit single, "Love Is the Drug".^[4] Frontman Bryan Ferry later called Gustafson a "wonderful player", adding, "“Love Is the Drug” wouldn’t have been anything without the bass playing. It really bought that track alive."^[5]

He was bassist on several tracks for Flamenco guitarist Juan Martin's 1981 concept album, Picasso Portraits (Flamencovision CD FV 03, 1994) namely: Harlequin – 1918, Desire Caught By The Tail – 1943, The Aficionado – 1912 and Girls of Algiers – 1955. Also played on Kevin Ayers' album The Confessions of Dr Dream, 1974.

In 1983 he was in the group Rowdy which included Ray Fenwick and Billy Bremner.

Gustafson was married to Anne Gustafson for over 30 years until his death.

With The Big Three

• At the Cavern Decca EP (1963)
• Resurrection Polydor (1973)

With The Merseybeats

• The Merseybeats Fontana (1964)
• On Stage Fontana EP (1964)
• I Think of You Fontana EP (1964)
• Wishin' and Hopin' Fontana EP (1964)
• The Merseybeats Greatest Hits Look (compilation album) (1977)
• Beats and Ballads Edsel (compilation) (1982)

With Quatermass

• Quatermass Harvest (1970)

With Bullet / Hard Stuff

• "Hobo" / "Sinister Minister" – Single (1971) Purple Records (as Bullet)
• Bulletproof Purple Records (1972)
• Bolex Dementia Purple Records (1973)
• The Entrance to Hell – different mix of Bulletproof (2010) (as Bullet)

With Roxy Music

• Stranded Island (1973)
• Country Life Island (1974)
• Siren Island (1975)
• Viva! Island (1976)

With Ablution

With Peter Robinson, Jayson Lindh, Jan Schaffer, Malando Gassama, Barry De Souza, Ola Brunkert.

• Ablution CBS (1974)

With Ian Gillan Band

• Child in Time Oyster (1976)
• Clear Air Turbulence Island (1977)
• Scarabus Island (1977)
• Live at the Budokan Virgin (1978)
• The Rockfield Mixes Angel Air (1997)
• Live at the Rainbow Angel Air (1978)

With The Pirates

• Lights Out/I'm into Something Good EP (1986), with Mick Green and Frank Farley
• Still Shakin Magnum/Thunderbolt (1988), with Mick Green and Geoff Britton
• Live in Japan Thunderbolt (2001), with Mick Green and Les Sampson

As contributor edit

• Jesus Christ Superstar (1969) On vocals.
• Joseph And The Amazing Technicolor Dreamcoat (1974) On bass.

With Roger Glover And Guests

• The Butterfly Ball And The Grasshopper's Feast (1974) John vocals on Watch Out For The Bat.

With Shawn Phillips

• Furthermore (1974)
• Rumplestiltskin's Resolve (1976)

With Steve Hackett

• Voyage of the Acolyte (1975) Bass on Star of Sirius

With Bryan Ferry

• Let's Stick Together (1976) Bass on Re-Make/Re-Model

With Gordon Giltrap

• The Peacock Party PVK (1981)
• Live Electric (1981)

With Joe Jammer

• Headway Angel Air (2015), recorded 1974 with Mitch Mitchell on drums

With Ian Paice, Tony Ashton, Jon Lord

• Malice in Wonderland (1977).

Solo album edit

• Goose Grease Angel Air (1997)

• Exclusive interview with John Gustafson, August 2007
• The Musicians' Olympus: John Gustafson at the Wayback Machine (archived 27 October 2009)
• Liner notes from re-release of Gustafson's 1975 album "Goose Grease"