The band are currently working on the follow-up to 2009's Sigh No More, which has been certified platinum in the US and four times platinum in the UK.
Speaking to Rolling Stone about their second studio set, bassist Ted Dwane explained: "The second record is just a reflection of our mindsets, where we're all at. It's doom folk, kind of like Black Sabbath meets Nick Drake."
The musician also admitted that the band were not expecting such a high level of commercial success when they first started out.
He added: "It's been really affirming because we started out with very humble aspirations. We never thought we'd be commercially viable and we were proved wrong."
Mumford & Sons' second studio album is expected to be released in 2012.
The group recently debuted a new track titled 'Ghosts That We Knew' during a live radio gig in the US.
Mumford & Sons' Sigh No More is the second-highest downloaded album from iTunes in 2011, despite the album being released two years ago.
Watch the music video for Mumford & Sons' 'Little Lion Man' below: