Burton moved to London with his sights set on a career as a trip-hop DJ. Once there, however, he decided to focus on producing his own hip-hop beats instead, taking a job as a bartender in a pub called The Rose to pay his bills. A friend convinced him to send his work to the British techno label Warp, and impressed with what they received (a mash-up of Air and Audio Two, and another of Nas and Portishead, as well as his own original beats), the label signed him to a two-record deal on their hip-hop offshoot, Lex. Now working under the pseudonym Danger Mouse -- the name of the title character of a cartoon he had watched as a child -- Burton moved back to the U.S. to record 2003's Ghetto Pop Life with Brooklyn MC Jemini, which was followed by 2004's Twenty Six Inch EP.
Grey Album, a mash-up of the Beatles' White Album and Jay-Z's Black Album, was leaked to the Internet. GQ magazine named Danger Mouse one of its top men of 2004, and Damon Albarn recruited him to work on Gorillaz's second album, 2005's Demon Days, which brought him a Grammy nomination for Producer of the Year. Danger Mouse also collaborated with MC MF Doom to form Danger Doom, whose debut album, The Mouse and the Mask, starring characters from The Cartoon Network's nighttime program Adult Swim, came out in 2005.
Danger Mouse joined Goodie Mob's MC/singer Cee-Lo in forming Gnarls Barkley. The duo's debut album, St. Elsewhere, went double platinum on the strength of the smash single "Crazy," which topped the U.K. charts and peaked at number two in America. A second release, The Odd Couple, followed in 2008. Late the next year he announced a new project with the Shins’ singer/guitarist James Mercer dubbed Broken Bells. Their self-titled debut album followed in 2010. Meanwhile, Danger Mouse continued producing and/or remixing material for a number of artists, including Sage Francis, Beck, the Black Keys, Bright Eyes, Dinah Washington, and Joker's Daughter. Team-ups continued. Before the end of 2010, Burton released Dark Night of the Soul, an album of songs written with Sparklehorse’s Mark Linkous, which featured cameos by Frank Black, Wayne Coyne, Suzanne Vega, Jason Lytle, Iggy Pop, and David Lynch, among others. At the beginning of 2011, Danger Mouse revealed that he had been working on a secret project for five years with Daniele Luppi called Rome, inspired by Italian film scores from the 1960s, with guest vocalists Norah Jones and Jack White.