"Nice to meet you, I'm John."

Translation: はじめまして、ジョンといいます。

[SupakuZe]

Wasn't といいます for "my name is" or "I am called" so "I'm John" should be "John desu"?

[Mathso2]

Both would be fine. In English, when you say you are <name> it is usually implied that that what you are called, so translating it to といいます is not a problem.