Valtteri Bottas. [Photo/IC]

Mercedes have confirmed Valtteri Bottas will partner Lewis Hamilton at the German team for the 2017 F1 season.

The 27-year-old Finn will replace current world champion Nico Rosberg after Rosberg shocked the F1 world, announcing his retirement in December just five days after taking the title.

Considered by many as a done deal weeks ago, Bottas was chosen over Mercedes reserve driver Pascal Wehrlein, who instead will take a seat at Swiss team Sauber for 2017.

"It's very exciting time for me," said Bottas at the announcement. "I think it's going to take a little while to understand that this is really happening. It's definitely another dream come true, to race in another team with such great history."

Mercedes team boss Toto Wolff expressed his confidence in the new signing. "The next weeks will be busy as we work to build relationships so Valtteri understands the team and the car. But that's an exciting challenge that will bring us fresh energy and a new dynamic between the drivers."

As a result of Bottas' move, Felipe Massa will come out of retirement and rejoin Williams, where he will mentor rookie driver Lance Stroll. The 35-year-old Brazilian will now take part in his 15th F1 season.

"I am very happy to have an opportunity to return to Williams," said Massa. "I always intended to race somewhere in 2017, but Williams is a team close to my heart and I have respect for everything it is trying to achieve."

The 2017 F1 season is set to get underway in Melbourne on March 24.