Jansen was born in South East London into a family of five and was educated at Catford Boys' School, leaving at 16. A self-taught musician since age 11, he switched from the guitar to drums at age 15 after feeling limited due to being left-handed.
He was a founding member of the group Japan, along with his brother David Sylvian (vocals, guitars and keyboards), Mick Karn (bass guitar), Richard Barbieri (keyboards), and Rob Dean (guitar), having all met at Catford. Japan began as an amateur group in 1974, while their first studio album entitled Adolescent Sex was released in 1978, followed by Obscure Alternatives the same year. Both albums saw polarized reviews and poor sales domestically in the UK, but were commercially successful overseas. The band's third album Quiet Life marked a significant departure from their original alternative glam rock style, with the change in sound causing them to be unintentionally associated with the New Romantic movement by critics, though this was repeatedly refuted by the members themselves. Virgin Records released Japan's final studio albums, Gentlemen Take Polaroids and Tin Drum, while the band had their last live performance on 16 December 1982. Japan suffered from personal and creative clashes and decided to split during a period when they were beginning to experience significant commercial success both in their native UK and internationally. The band briefly reunited in 1991 under the name Rain Tree Crow and released a self-titled album.
After Japan's break up, Jansen recorded with bandmate Richard Barbieri under the name Jansen/Barbieri and released an album (Catch The Fall) as The Dolphin Brothers, with Jansen handling lead vocals as well as drums and percussion.
In 1991, Jansen, Barbieri, and Karn formed Medium Productions as a venue for releasing their own music, as well as releases by other artists.
Jansen has worked extensively as a session musician and in collaboration with a wide range of international artists, such as Yukihiro Takahashi and Italian singer-songwriter Alice. He collaborated with David Sylvian and Burnt Friedman on the Nine Horses project, which has given birth to one album and one extended play CD released through Sylvian's record label Samadhi Sound. Jansen performed with Sylvian during his live tours, playing drums and percussion.
He released his first solo album, entitled Slope in 2007. Regarding the creative process behind the album, Jansen stated that he "approached composition attempting to avoid chord and song structures and the usual familiar building blocks. Instead I wanted to piece together unrelated sounds, music samples, rhythms and 'events' in an attempt to deviate from my own trappings as a musician." The album was released on Samadhi Sound, and features Sylvian in a "bluesy" duet with Joan Wasser, and contributions by Anja Garbarek, Sweet Billy Pilgrim, Thomas Feiner and Nina Kinert. On 15 April 2016 Jansen released a second solo album entitled Tender Extinction via Bandcamp and other digital music retailers.
Jansen has continued to work on new compositions, some of which he has released as stand-alone tracks, and continues to be in demand as a producer and collaborator, working with musicians across a range of genres. A recent re-release of the 1995 Jansen/Barbieri album Stone To Flesh includes a new track entitled "Map of Falling," composed by the two musicians in 2015.
During his time with Japan, Jansen dabbled in photography, documenting the band and their transient lifestyle. He held small-scale photographic exhibitions in Tokyo and London during 1982 and 1983, respectively. A selection of these images are available on his website. In October 2015, Steve released a book of his photography entitled Through A Quiet Window through the Japanese publisher Artes Publishing.
Jansen maintained a Tumblr blog under the username of "Sleepyard" as an additional avenue to publish his photography and answer fan questions, but wrote a post on April 2, 2016 stating that he would no longer maintain it, citing his displeasure with the platform as a whole. Later in the same month, Jansen re-launched his blog through WordPress.
Jansen is an atheist and describes astrology as "almost as bonkers as religion."2007 – Slope (Samadhi Sound)
2016 – Tender Extinction
2017 – The Extinct Suite
1977 – Adolescent Sex (Hansa Records)
1978 – Obscure Alternatives (Hansa Records)
1979 – Quiet Life (Hansa Records)
1980 – Gentlemen Take Polaroids (Virgin records)
1981 – Tin Drum (Virgin Records)
1981 – Assemblage (compilation) (Hansa Records)
1983 – Oil on Canvas (live album) (Virgin Records)
1984 – Exorcising Ghosts (compilation) (Virgin Records)
1989 – Souvenir From Japan (compilation)(Hansa Records)
1991 – The Other Side Of Japan (compilation) (Receiver Records)
1991 – Rain Tree Crow (Virgin Records)
1985 – Worlds In A Small Room (Pan East (UK) / JVC Victor (Japan))
1991 – Stories Across Borders (Venture / Virgin)
1995 – Stone To Flesh (Medium Productions)
1996 – Other Worlds In A Small Room (Medium Productions)
2015 - Lumen (KScope)
2015 - Stone To Flesh (KScope) re-mastered with additional track Map of Falling
1994 – Beginning to Melt (Medium Productions)
1994 – Seed (Medium Productions)
1999 – ISM (Polydor / Medium)
2001 – Playing in a Room with People (Medium Productions)
1987 – Catch the Fall (Virgin Records)
1987 – Face To Face (Japanese T.V.C.M. 7" Single) (Virgin Records)
(Also included on Virgin Japan CD release of Catch The Fall)1997 – Changing Hands (Medium Productions)
"Stay Close" 12 inch EP with Yukihiro Takahashi (Pony Canyon Japan, Rime Records UK 1986)2009 - "A Secret Life" (Metamatic Records)