The Cameroom international becomes the first signing under new director of football Oliver Kreuzer, and the player said that he is "very happy" to have joined Hamburg.
"I'm very happy to be here at this great club, in this great city," Bundesliga.com quotes Zoua as saying.
"Hamburg are a fantastic club and it's a huge thing for me to be playing in the Bundesliga. That apart, Thorsten Fink certainly played a role as well in my decision to move here.
"I also spoke with our national team coach Volker Finke, and he filled me in on what a great, tradition HSV have. He's confident a move to the Bundesliga will be very good for me and for my development as a footballer."
Zoua has three caps for Cameroon.