The pair forged a formidable partnership when they raced together for three years at HTC-Highroad between 2009 and 2011 before going their separate ways when the team disbanded.
Olympic silver medallist Rigoberto Uran has left Team Sky to join Omega Pharma-Quick Step, the Belgian team have also announced.
The 26-year-old Colombian, who finished second in the road race at last year's London Games, was also runner-up in this year's Giro D'Italia after taking over the team leader's role from Bradley Wiggins.
"Rigoberto's arrival reinforces our team as far as the major tours are concerned," team manager Patrick Lefevere said in a statement. "Uran is a top rider and his talent on climbs goes without saying."