The folk rock group teamed with 'The Wire' star to make the clip for 'Lover Of The Light' - the second single from their 'Babel' album - which was shot in Pembrokeshire, Wales.
The band said in a statement: ''We are, quite obviously, huge fans of Idris Elba's acting work, as pretty much anyone can agree he's the most badass British actor since [TV star] Richard Briers. So we trusted him as the director for our latest video.''
The group also found making the video - in which Idris also stars,- was one of the their most enjoyable experiences to date.
They added: ''We've been fortunate to work with some great directors in the past, but we've always been uncomfortable with the process of making music videos. We've never really enjoyed being in them, unless they involve live performance.''
The idea for the clip came from Idris, scriptwriter Dan Cadan and the band, and was developed over a drinking session in a pub.
The band added: ''Talking to Idris and Dan about making a video that we're not in made it a lot more fun to think about. They went off and wrote the treatment after our ale-infused conversation in a pub in London, and what they directed, we are proud to present as 'Lover of the Light'.''
Mumford and Sons release a new live DVD, 'The Road To Red Rocks', on November 26 and are also playing live in the UK this month for the Tour of Two Halves, which has completely sold out.