Bottas fills the gap at Mercedes left by reigning champion Nico Rosberg, who retired at the end of last season.
And with the season opener at Australia just five days away, all eyes will be on the Finnish driver on how he will cope up against Lewis Hamilton.
Mercedes have dominated the sport, winning the last three Constructor's Championships and 51 of the last 59 races.
But Bottas is looking forward to prove he can compete with the best.
Valterri Bottas is looking forward to proving himself at Mercedes
Bottas believes he can thrive under the pressure of battling with Lewis Hamilton
"I am really excited about the new season in Formula One," said Bottas. "It is a new era with the regulation changes as well as me changing to a different team.
"It is a great challenge for everyone, but especially for me. Mercedes has been winning for the last three years so it is kind of a dream come true for me to be in a team like this.
"It is a big year ahead and it is a great opportunity, but there is no doubt I will definitely need to prove myself to a lot of people and the team that I deserve my place.
"I see things very positively and I see it as a great opportunity for my career to fight for the wins and hopefully even for the world championship."
Everything you need to know about Valtteri Bottas
Tue, January 10, 2017
Express Sport brings you everything you need to know about Valtteri Bottas, with the Finnish driver joining Lewis Hamilton at Mercedes after Nico Rosberg's retirement
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Express Sport brings you everything you need to know about Valtteri Bottas
Bottas is yet to win a Formula One race from 77 starts but he was fighting with a mid-table Williams car.
Now he will be expected to fight for the front row every race but Bottas believes he can thrive under the pressure.
"I don't fear that I will be the number two at Mercedes," Bottas added.
"Mercedes do not have a number one, or a number two driver, so it is up to me to perform. As long as I do my job, which is to perform on the level where the car should be, we are all good and I know I can do it.
Bottas is getting ready for his first season at Mercedes with the first race weekend just days away
2017 F1 Calendar
Wed, January 18, 2017
Express Sport brings you the complete Formula One 2017 race calendar
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Express Sport brings you the full Formula One 2017 calendar
"I am very excited about going up against Lewis. He is a three-time world champion and a great reference point. Everybody knows exactly how good he is as a driver.
"It is great to be a team-mate of Lewis and I hope we can have a strong year in this era of Formula One.
"In testing we managed to work well together and there was a good team spirit. I see no reason why it should not continue like that."