Wehrlein, who is part of Mercedes' young driver programme, made his Formula One debut at the Australian Grand Prix for the Mercedes-powered Manor team in March this year.
The 21-year-old has finished all five of his races in F1, with a 13th place in Bahrain his best result to date, and is highly rated by Mercedes boss Toto Wolff, who calls him the "little prince".
With rumours escalating that championship leader Rosberg has been offered a contract with Ferrari, Wehrlein is heavily tipped to step into the vacant drivers' seat at Mercedes next season.
And the German believes he is more than ready to make the step up should Rosberg decide to make the Ferrari switch.
"Of course there is something in my head - but that’s for me! Of course I want to sit in a Mercedes cockpit as fast as possible," Wehrlein told Formula1.com.
"And then the full program: win races and championships. But first is learning. No doubt would it be incredible to sit in the Mercedes next season.
"When I spoke with Toto some months ago he said that Mercedes couldn't put young drivers without experience into our team. That would be too high a risk.
"But now I would have one year of experience under my belt… In the end it is Mercedes' and Toto's decision if that one year is enough experience.
"I am ready, for sure. And regarding the 'little prince': little princes tend to become kings one day!"