Bernhard Eisel has signed a three-year contract extension that will see him remain at Team Sky until 2015.
"The fact that Mark Cavendish is leaving us made this one of the toughest decisions of my life, and I wouldn't have stayed if I hadn't felt absolutely at home here," said the 31-year-old.
"Mark and I have ridden together since 2007 and he was my only room mate during most of that time. I haven't just looked after him on the bike, I also regard him as a brother, so it will be strange competing against him in the future."
Cavendish left the British team to join Omega Pharma-Quick Step, who will support the 'Manx Missile' in his bid for stage wins.