Shortly after the dawn of the '90s, Carcass expanded to a quartet, as Michael Amott signed on as second guitarist, resulting in two more favorites of the metal underground, 1991's Necroticism: Descanting the Insalubrious and 1992's four-song EP Tools of the Trade. Whereas he once sang in a growling voice à la a dragon desperately in need of some Pepto-Bismol, Walker adopted a slightly more traditional metal singing style, while the band was no longer afraid to let Iron Maiden-esque guitar work enter the mix. The result was the group's major-label debut for Sony, 1994's Heartwork. Although Heartwork is probably Carcass' best-known album, fan reaction is often split evenly between those who feel the group had sold out with a more easily digestible sound (quite comparable to thrash metal) and those who feel that it's one of the '90s great metal releases.

Either way, Amott left the group around this time, and was replaced by Carlo Regadas for Carcass' final studio album, 1996's appropriately titled Swansong. The same year, a compilation of rarities was issued, Wake Up and Smell the Carcass. Subsequently, Owen, Walker, and Regadas continued working together for a spell under the Blackstar name; Amott formed both Spiritual Beggars and Arch Enemy; and Steer surprisingly formed a blues-rock power trio, Firebird.