Cavendish is leaving after Manchester, England-based Sky focused its priority this year on team leader Bradley Wiggins, according to the team website. Wiggins became the first British winner of the Tour de France in July.
Cavendish, 27, took his 23rd stage win on the last day of the French race, moving him ahead of Lance Armstrong and into fourth place in the all-time list.
Cavendish won three Tour de France stages with Team Sky including the final-day sprint after Wiggins was among riders to help lead him to the finish line.
With the HTC-Highroad team in 2011, Cavendish won five stages and took the green jersey as the first British winner of the points classification.
Seven-time champion Armstrong was stripped of his race wins by the U.S. Anti-Doping Agency in August.
His former teammate Levi Leipheimer was fired by Omega Pharma two days ago after he admitted doping earlier in his career in an affidavit published by USADA.
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