The award was announced during a music-packed ceremony at London's Grosvenor House Hotel, the BBC reported.
The winners led by New York-based singer Antony Hegarty, beat fellow nominees Coldplay, Kaiser Chiefs, K.T. Tunstall, Seth Lakeman, Bloc Party, Polar Bear, Maximo Park, The Magic Numbers the Go! Team and MIA.
The 20,000 pound (about $36,800) award to the most creative British or Irish album of the year is decided by a panel comprised of industry experts, journalists and artists.
"I think they must have made a mistake," the BBC quoted the suprised Hegarty as saying. "I am completely overwhelmed. I think that's insane."
Hegarty told emcee Jools Holland he found the competition to be a "big nutty."
"It's kind of like a crazy contest between an orange and a spaceship and a potted plant and a spoon -- which one do you like better?" he said.
Previous Mercury winners include hip-hop's Dizzee Rascal and rockers Primal Scream, P.J. Harvey and Franz Ferdinand.
2014: The Year in Music [PHOTOS]