Sheringham Shoals, which will have a capacity of 315MW, is located off the English coast and has been in development since late 2009. It is jointly owned by Norwegian companies Statkraft, a utility, and oil and gas business StatoilHydro.
According to the wind farm's developers the bomb was discovered at the northwest end of the site as part of pre-construction preparations.
The bombs was found by divers from underwater specialist Red7Marine and detonated by disposal expert MACC International.
Siemens is to supply the 88, 3.6 MW turbines for the wind farm under a €450 million contract which includes servicing the machines.
They are being erected 17-23 kilometres off the town of Sheringham on the north Norfolk coast and cover an area of 35 square kilometres. The facility is to start operation in 2011.