The 21-year-old's previous deal had been due to expire at the end of the season.
"I am happy to be at Nurnberg," Plattenhardt told the club's official website.
"It's the place where I have been handed the chance to make my very first steps in the Bundesliga and I am sure this is the best club to develop further."
Nuremberg general manager Martin Bader added: "We are happy to have agreed a new contract with Marvin. It's good to know he has pledged his future to our club. At this point in time, this signature is a great thing."
Plattenhardt has made 13 Bundesliga appearances this season.