Avenged Sevenfold was formed by the original members: vocalist Matthew Sanders (M. Shadows), guitarist Zackary Jonathon Baker (Zacky Vengeance), drummer Jimmy Owen Sullivan (The Reverend Tholomew Plague) and bassist Matt Wendt.

Although the band had no religious message or mission, their name is a reference from the bible story of Cain and Abel from the scripture "You shalt suffer Vengeance Seven Times Over".

Between the years 1999-2000, the band recorded two demos, before Matt Wendt left the band in 2000 and was promptly replaced by Justin Sane, who also played the original piano track on the song "Warmness On The Soul". Simultaneously, the band drafted in lead guitarist Brian Haner Jr. (Synyster Gates), completing the first 5 piece line up for the band.

Some of the members had also been in numerous other bands together including Pinkly Smooth, (The Rev on vocals and Gates playing guitar) releasing a single EP before going on indefinite hiatus. The Rev and Justin Sane were also in the band Suburban Legends.

The band continued actively promoting their demo's between 2000-01 before Justin Sane left the band in late 2000, to be replaced by Daemon Ash.

In 2001, the band released their first album with Good Life Recordings: to generally mixed reviews, however it was generally acclaimed for showing that the band had a good strong Metalcore style in the album. The album was subsequently re-released when the band changed labels the following year to Hopeless Records, with an alternative front cover and featuring Synyster Gates playing the introductory piano track "To End The Rapture".

The band finally received recognition and began performing with bands like Mushroomhead and Shadows Fall on the Take Action Tour. They also settled on their fourth bassist, Jonathon Lewis Steward (Johnny Christ).

In 2003 the band released their second album, Waking the Fallen on Hopeless Records and their first video to the song "Unholy Confessions", which went into rotation on MTV's Headbangers Ball. The album received massive critical acclaim from the underground metal scene mixing their previous Metalcore style on their previous album with melodic harmonies. Shortly after the album released, A7X signed to Warner Bros. Records.

The band achieved mainstream success with their major label debut and third album released in 2005: City of Evil which sold over 30,000 copies in its first week. The album showed a significant change in music style to the band's previous albums most noticeably, the absence of M. Shadows screaming. City of Evil also featured former bassist Justin Meacham (Justin Sane) playing piano on the track "Sidewinder"

Ron Anderson, who made a reputation working with Axl Rose and Chris Cornell, worked on a voice with Shadows that had "grit while still having the tone". The band went on to win "Best New Artist" (despite hardly being newcomers) in 2006 at MTV's music awards.

Avenged Sevenfold went on to their "Cities of Evil" tour, as well as this, they earned an invitation to the Ozzfest 2006. They toured the US, UK mainland Europe, Japan & Australasia before cancelling their Fall 2006 tour to record new music.

The band released their fourth album; Avenged Sevenfold, in 2007 which received large acclaim and debuting at #4 on the Billboard 200. The self-titled album has to date sold over 500,000 copies and received "Album of The Year" at the 2007 Kerrang! Awards.

In 2008-09, the band headlined the 2008 Taste of Chaos tour, before releasing a Live DVD/B-sides CD called Live in the LBC & Diamonds in the Rough. The DVD featured a full live performance of the band at the LBC Arena in California, while Diamonds in the Rough featured previously unreleased tracks and covers including Iron Maiden's "Flash Of The Blade" and Pantera's "Walk" (which was also performed on their live DVD).

Devastation lay ahead for the band when on 28th December 2009, The Rev (James Owen Sullivan) was found unresponsive at his home in California. The following morning he was pronounced dead, and after early speculation toxicology results came back positive for Acute Polydrug Intoxication as a result of combined Oxycodone, Oxymorphone, Diazepam/Nordiazepam and ethanol effects. A private funeral was held before Jimmy was laid to rest the following January.

The band now faced the tough decision to finish their fifth album and did with the aid of Mike Portnoy (famously drummer for Dream Theater) who humbly accepted the offer. In addition shortly after the completion of recording, the band announced their first USA, UK and European tours since the death of The Rev, with Mike coming along for the States tour dates.

Avenged Sevenfold's fifth studio album Nightmare was released on 27th July 2010. The album received massive response from both the underground and mainstream scenes, and within a week of its release had reached 5th in the UK album charts, sold around 163,000 copies and debuted at number 1 on the Billboard 200.

After the Nightmare world tour, Mike Portnoy ceased working with the band and was replaced by Confide's drummer Arin Ilegay, who eventually took the place of the late James Sullivan as the bands permanent drummer in 2011.