Disaffected were formed in 1991 in Cascais, Portugal as a death/thrash band by the drummer Joaquim Aires and the guitarist Sergio Paulo. Later adding Zakk (guitar) and Sergio Monteiro (bass), the band released the ...After... demo in '92, and later that same year they were included in The Birth Of A Tragedy (MTM '92), a vinyl compilation of Portuguese metal bands with the song "Echoes Remain".

In 1993 line-up changes ensued as they recruited the bass player Antonio Gião, the vocalist Gonçalo Cunha and the guest vocalist Nuno Loureiro (Exiled) to perform a lot of shows with.

Later their music had become more progressive and complex, and in 1994 the keyboard player Fátima Gerónimo and vocalist José Costa (Sacred Sin) joined the band as they got signed by Skyfall Records, which led to the release of their debut full-length Vast in 1995.

Disaffected's Vast, which includes "Thou Art Lord" (Acheron cover), was recorded at Namouche Studios (Lisbon) and produced by Marsten Bailey.

A videoclip for the song "Vast - The Long Tomorrow" was recorded to promote the album Vast and was aired on MTV, VIVA, MCM and RTP (Portuguese Television).

In 1996, they've also covered "Seasons In The Abyss" for the Slayer tribute album Slatanic Slaughter II (Black Sun Records '96).

The band was split up between 1997 and 2006.

In 2006, keyboard player Bianca (replaced in 2011 by Rodrigo Domingues) and drummer Octávio Custódio joined the band and the reunion happens.

In 2011 the band sign a record deal for a worldwide release with the German label Massacre Records.

The new album called Rebirth, produced by Fernando Matias at The Pentagon Audio Manufacturers Studios, was released worldwide on May 25, 2012.

On May 30, 2012, the band released an official video for "The Rebirth Of...". The song comes off Disaffected's 2nd album Rebirth and the clip was directed by Mafalda Norte and Frederico Weinholtz.

In February 2014, keyboard player Filipa Alçada joined the band, replacing Rodrigo Domingues.