Dong already owns the Borkum Riffgrund project, which is located 55 kilometres off the north-west coast of Germany.
According to Dong, the new development could have a 400MW capacity, based on space for 80 turbines.
Speaking about the deal, Dong CEO Anders Eldrup said: "A robust pipeline of projects in key offshore wind markets is essential for DONG Energy’s ambition to maintain our position as the leading player in the offshore wind industry."
Dong’s 320MW Borkum Riffgrund project is set to come online in 2014. It will use Siemens 3.6MW turbines.