Extreme was formed in Malden, Massachusetts, in 1985. Vocalist Gary Cherone was in a band with drummer Paul Geary, and guitarist Nuno Bettencourt was in a band with bassist Pat Badger. Following an altercation between the rival groups over communal dressing rooms Cherone, Geary, Bettencourt, and Badger decided to form a new band.

Cherone and Bettencourt began writing songs together and played numerous shows in the Boston area. The band gradually developed a strong local following, and was named "Outstanding Hard Rock/Heavy Metal Act" at the Boston Music Awards in 1986 and 1987.

The band had accumulated approximately 55 songs by the time A&R director Bryan Huttenhower signed them to A&M Records in 1988. The band then recorded their self-titled debut which was issued in 1989. The first single was "Kid Ego," a song that Cherone would later admit made him cringe. The final track on the album, "Play With Me," was used as the "mall chase" song in Bill & Ted's Excellent Adventure.

Moderate sales of Extreme's first record were sufficient to support a second release. Michael Wagener, who had previously worked with Dokken and White Lion, was engaged to produce Extreme II: Pornograffiti (1990).

The record, which showcased Bettencourt's guitar-playing, was a mixture of funk, pop and Glam metal sounds. "Decadence Dance" and "Get the Funk Out" were released as singles. "Get The Funk Out" reached number 19 in the UK charts in June 1991. Neither single was successful in the United States, however, and the album had fallen off the charts when A&M sent the third single to a number of radio stations in Arizona.

The acoustic ballad "More Than Words" entered the Hot 100 on March 23, 1991, at Number 81. It later became a huge smash, hitting Number 1 on Billboard's Hot 100 in the United States. The subsequent single, "Hole Hearted," another acoustic track, was also successful, rising to Number 4 on the same popular music chart.

The band began recording of their third album in 1992. Their appearance at the Freddie Mercury Tribute Concert in April 1992 interrupted the recording sessions, but it gave the band considerable exposure beyond the heavy metal fraternity. III Sides to Every Storywas released on September 22, 1992. Sales were disappointing, however. The video for the first single, "Rest in Peace," was inspired by a film short by the National Film Board of Canada called Neighbours. The band was sued, but they quickly settled out of court, later releasing a new version of the film clip. The album contained noticeable Christian themes, presumably put there by Cherone, who noted in interviews being interested in evangelical preachers.

Prior to the band's appearance at the Donington's Monsters of Rock festival in the summer of 1994, Mike Mangini (ex-Annihilator) replaced Geary on drums, who left to pursue a career in the business side of the music industry, managing successful acts such as Godsmack.

The subsequent record Waiting for the Punchline, released on February 7, 1995, containing the singles "Hip Today," "Unconditionally," and "Cynical," was less successful than III Sides to Every Story. Finally, Extreme disbanded in 1996, on amicable terms.

In 1996, Gary Cherone joined with Van Halen for their album Van Halen III, issued in 1998 only to leave the group in 1999 and later form Tribe of Judah which released an album called Exit Elvis in 2002. In 2005, Gary released a four song sampler CD, entitled Need I Say More.

Nuno Bettencourt went on to release a solo album titled Schizophonic in 1996. In 1998 he formed a group called Mourning Widows and released a self-titled album that year and a follow-up album Furnished Souls For Rent in 2000. Following the breakup of that band, he released another solo album under the project name of Population 1 in 2002. Forming another band, they decided to keep the name of Population 1 and released a five-song E.P. entitled "Sessions from Room 4" in 2004. They changed the band's name to Dramagods and created the follow-up CD entitled Love in 2005.

A 13-track Extreme "best-of" collection, The Best of Extreme - An Accidental Collication of Atoms?, was released in 1998. A re-packaged collection with a different tracklisting was also released in 2002 simply titled Extreme - The Collection.

Extreme reformed for a short tour in 2004 playing in their hometown Boston at the WAAF anniversary as well as a few concerts in Japan and Azores. After a hiatus during 2005, the band returned in 2006 with the "classic" Pornograffitti line-up to do a small three-show reunion tour in New England.

On November 26, 2007, the band announced plans for a world tour during Summer 2008 with King's X as well as a release date and label for the new album, Saudades de Rock, produced by Bettencourt. Kevin Figueiredo, who played with Bettencourt in DramaGods and Satellite Party, took over drum duties. Original drummer Paul Geary is still involved with the band albeit in a management position. Singles from the album have been available on MySpace including "Star". The release dates of the CD were July 28, 2008 for France, August 4, 2008 for Europe, and August 12, 2008 for the USA.