Sylosis was formed in 2000[4] by guitarist Josh Middleton and bassist Carl Parnell who began playing extreme metal with other friends from school.

[5] Sylosis released a couple of EPs; 2006's Casting Shadows and 2007's The Supreme Oppressor in the UK on a small indie label, In at the Deep End Records.

In December 2007 Sylosis signed with Nuclear Blast Records, and they released their debut album Conclusion of an Age in October 2008.

[5] On the style of their debut album, Conclusion of an Age, Middleton remarked, "The foundation of our sound is old school Bay Area thrash.

[citation needed] Sylosis replaced Rise to Remain during the UK leg of As I Lay Dying's European tour in 2010.

[8] On 25 September, the members of Sylosis were involved in an RV accident, the injuries from which resulted in the withdrawal of their shows supporting Trivium and DevilDriver.

[9] After the members of Sylosis had recovered from their respective injuries, they embarked on a tour of the UK and Europe as main support to DevilDriver with Bleed from Within.

In late September 2014 it was announced that Rob Callard was stepping down as drummer of Sylosis after nine years of playing in the band.

[citation needed] At the start of October 2014, Sylosis announced details of their fourth album Dormant Heart, which was released on 12 January 2015 through Nuclear Blast Records.

[10] On 5 December 2019 Nuclear Blast revealed the pre-order for an apparent new record titled Cycle of Suffering, to be released on 14 February 2020.

"[18] On June 1, they announced their sixth studio album, A Sign of Things to Come, along with the single and music video "Poison for the Lost.