Skjelbred has signed a three-and-a-half year contract with the German side, but will not join the club until his contract with Rosenborg expires on January 1, 2012.
“During my time at Nurnberg, I tried to sign him but the deal never happened,” Hamburg coach Michael Oenning told the club’s website.
He added: “We are trying to get him earlier. We will just have to wait and see what the coming days bring.”