The 30-year-old, who has a wealth of Grand Tour experience, is joined at the British squad by Scotland’s Andrew Fenn, Czech rider Leopold König, Dutchman Wout Poels and Norwegian Lars Petter Nordhaug, who has re-signed for Team Sky after two years away.
Roche’s signing is significant as it strengthens Chris Froome’s support for the 2015 Tour de France, while simultaneously weakening Alberto Contador’s squad as the Irishman was previously at Tinkoff-Saxo.
Roche, the son of 1987 Tour de France winner and world champion Stephen Roche, said: “It’s a great honour to sign for Team Sky and I have the opportunity to ride with some of the best riders in the world. I feel that I’m still developing as a rider so now’s the perfect time to join Team Sky and to continue my upwards path.”
Team Sky principal Sir Dave Brailsford said: “He brings a wealth of experience, having ridden 13 Grand Tours in his career, and that will be invaluable to the team. Nicolas has the perfect character and temperament for us and we expect him to play a key role next season.”
König is also likely to play a strong support role for Froome, while also riding Grand Tours for a high placing himself.
While with Team NetApp-Endura, König placed seventh in the 2014 Tour de France and he has claimed stage wins at the Vuelta a España, Tour of California and Tour of Britain.
The 24-year-old Fenn becomes Team Sky’s first Scottish rider, after moving from Mark Cavendish’s Omega Pharma-QuickStep squad. Poels becomes the first Dutchman at Team Sky and the climber has been watched by the squad for some time, while Nordhaug returns after a three-year stay from 2010 to 2012.
Brailsford added: “We’ve signed five quality riders for next season and each one of them will help strengthen and enhance the squad. We have a strong nucleus of riders at Team Sky and these signings will be excellent additions to the squad. They all bring their own qualities and we’re looking forward to welcoming them to the team and seeing them in action next season.”