The 27-year-old, who won the Tour of Britain, has penned a two-year deal after leaving Endura Racing.
The Plymouth climber also claimed overall victory in three more stage races in 2012 - the Tour de Mediterranean, Tour du Haut Var and Tour Alsace - and was highly prevalent at the World Road Championships.
Tiernan-Locke said: “It’s an incredible opportunity for me to step up from the UCI Continental ranks, and although I’ve really enjoyed my time at Endura, I couldn’t pass up the chance to join the world’s best team.
“When you look at the season Team Sky have had, to even be considered by them was a massive honour for me, so I’m over the moon to be riding for them in 2013.
“This season’s results have given me a lot of confidence and I can’t wait to compete at the very top of the sport. I’m under no illusions - it’s going to be a big step up - but with all the support I’ll receive from the coaching staff, and having such talented riders around me, I’ll definitely be looking to up my game.”
Tiernan-Locke joins fellow newcomers Dario Cataldo, Vasili Kiryienka, Gabriel Rasch, David Lopez, Joe Dombrowski and Ian Boswell at Team Sky and team principal Dave Brailsford was upbeat about the signing.
“At Team Sky we are determined that the best British talent have the opportunities to compete at the highest level of our sport. We have monitored Jonathan’s progress closely and are delighted to offer him this contract," said Brailsford.
"He has worked hard to get himself to where he is today and deserves his chance to compete against the very best cyclists in the world.
“Next season will be a great opportunity for him. We believe he is in the best place to achieve his full potential and are looking forward to having him on the team."