In 1989 Jan Rechberger and Esa Holopainen played in a speed metal band Violent Solution, which Tomi Koivusaari had left the previous year to form up the death metal band Abhorrence. Violent Solution slowly withered away as the musicians involved became interested in other things and styles of music. At this point, Jan Rechberger and Esa Holopainen had the idea of putting together a death metal band. In early 1990, Tomi Koivusaari was asked to be the vocalist and Oppu Laine to be their bassist.

During that time the band asked Tomi to pick up the slot of rhythm guitarist as well as singing, which led to the band dumping all original compositions and starting again. With the band starting to move along, Tomi's other band (Abhorrence) split up and he found himself with much more time to put into Amorphis. The band went into gear and started churning out new brutal music.

Shortly after the band had recorded their first studio demo tape, Tomi got a letter from Relapse Records offering Abhorrence a recording contract. Since Abhorrence was no longer active, they quickly sent their own demo in the return mail and eventually got signed to a recording deal. The deal would later almost destroy the band, due to a very long commitment and poor artist relations. They quickly released a death metal classic The Karelian Isthmus and would later release the demo in the form of the Privilege of Evil EP. The EP featured Abhorrence's original vocalist, Jukka Kolehmainen, as a vocalist on the Abhorrence cover song Vulgar Necrolatry.

The band quickly adopted new ways of making music and started incorporating different styles in with the original death metal aspect, creating a unique and complex soundscape. With its sophomore release the group reclaimed its Finnish heritage in triumph, creating a monumental album that is nowadays considered an all-time classic: Tales from the Thousand Lakes, a concept album based on the Finnish national epic, the Kalevala. This 1994 release, while still strongly rooted in the death metal tradition, is considered to be the first significant step toward a new direction as melodic clean vocals were added, provided by Ville Tuomi.

The success of Tales was immediate and overwhelming. The ensuing tours and tough schedules, however, took their toll, and Kasper (keyboards) soon decided to leave the band. A successor was found in Kim Rantala. Jan was replaced by Pekka Kasari (ex-Stone), and just before recording their third album, Amorphis recruited a sixth member, singer Pasi Koskinen. The third album, Elegy (1996) became a quantum leap for Amorphis, the watershed between their death/doom beginnings and the unique brand of progressive rock that has been the cornerstone of their albums ever since. Lyrics were again adapted from Finnish mythology, in this case, the Kanteletar, a collection of ancient folk poetry. Pasi and Tomi shared the vocals on a roughly equal basis, with Pasi's role restricted to the clean parts.

After about one and a half years of extensive touring following the release of Elegy, the band members opted for a time-out to recharge their batteries and think about new material. Their next offering, 1999's Tuonela was a mellow guitar album, although toward the end of the studio sessions, Santeri Kallio of Kyyria was brought in to add some tasteful keyboard tracks to the songs. New instruments were introduced (Tomi playing sitar in the song "Greed", Sakari Kukko saxophonist/flutist also provided some foreign spices) and the death grunts were now almost totally abandoned, as all vocals were performed by Pasi.

The new millennium was greeted with the tenth-anniversary compilation Story and another line-up change. Following the breakup of Kyyria, Santeri had already joined Amorphis as a full-time member when bassist Oppu felt he could no longer commit himself to the band. He was succeeded by another ex-Kyyria member, Niclas Etelävuori, who came in just in time for Amorphis' third U.S. tour.

Am Universum, released in 2001, retained the moody atmosphere of Tuonela but introduced more varied soundscapes and a much wider dynamic range. More space was given to keyboards and saxophone work, the latter again contributed by Sakari Kukko. It was a more experimental album, and arguably Amorphis' most psychedelic to date. In 2002 the band was asked for a contribution to the soundtrack for the movie Menolippu Mombasaan. The commissioned piece was a cover version of a 1976 Finnish pop hit, "Kuusamo", which was given the full Amorphis treatment and remains the band's only song in their native tongue to this day.

Amorphis' longstanding relationship with Relapse Records ended with Am Universum. In 2003, Relapse released the retrospective Chapters, which included a DVD featuring the band's videos from "Black Winter Day" to "Alone". Far from the Sun was produced by the band itself, which had been rejoined by original drummer Jan Rechberger after Pekka Kasari had quit to concentrate on family duties. Compared to Am Universum, Far From The Sun turned out heavier, more straightforward and also once again more folk-oriented, journeying deep into Turkish and Persian territory. The album would have been accompanied by a North American tour in 2004 but it was ultimately canceled for reasons beyond the control of the band, yet the prospect of it gave Pasi, father of two small children and involved in numerous other musical projects, the reason he had been looking for to leave the band after nine years. Amorphis found his replacement, Tomi Joutsen (Sinisthra), through word of mouth.

The band's latest release is Eclipse.