Mark Cavendish joined Omega Pharma-QuickStep after negotiating a release from Team Sky 12 months into a three-year contract.
The 27-year-old from the Isle of Man had privately expressed a desire to move on in July at the Tour de France, before going public in September, believing Team Sky's stated ambitions and his own no longer matched.
Cavendish said: "After a year of being part of the successes at Team Sky I've decided to leave to join Omega Pharma-QuickStep Cycling Team to pursue different goals."
Earlier this week Cavendish was preparing for a second season with Team Sky after protracted talks over an early termination broke down. Press Association Sport understands Team Sky relented and waived a release fee, allowing the Manxman to move on and sign a three-year deal with the Belgian team.
He added: "It's been an incredibly fun year riding with friends I've grown up with but I'm super excited about riding with old friends and team-mates in one of the most successful and established teams in cycling. I believe in the team's project and I'm thrilled to be a part of it."
The Manxman, who won the points classification green jersey at the 2011 Tour, claimed the world title in September 2011 and joined Team Sky a few weeks later.
He was part of the team which helped Bradley Wiggins become the first British winner of the Tour and won the final stage for a fourth successive occasion in Paris. It was his 23rd Tour stage win, taking him to fourth in the all-time list and within reach of Eddy Merckx's record haul of 34.
He suffered disappointment in the Olympic Games road race, his major objective for the season, and spoke publicly of his wish to leave Team Sky on the eve of the Tour of Britain last month, comparing the situation to a long-distance relationship.
Team Sky principal Dave Brailsford, meanwhile, paid tribute to Cavendish, saying: "Mark has been a true champion for Team Sky this year. It's been an honour having the rainbow jersey in this team and great to work so closely with a rider I've known since he was a junior.
"The sight of him winning in Paris, with the yellow jersey leading out the world champion - both in Team Sky kit - is something you'll never forget. We all wish Mark the very best with his future ambitions in a new team and as British rider."