The project site, 27 kilometres off the UK's east coast, was known to have previously been used for military exercises and saw significant conflict during World War II, said Dong.
The developer said the most notable item was a German Luftmine B ground mine that contained a net explosive quantity of 698kg of Hexonite.
Swedish UXO specialist MMT was contracted to carry out the controlled detonations of 36 live explosives at the site. Five items were deemed safe and recovered to shore to be destroyed.
A marine mammal observation team, which was present during the controlled explosions, reported "very low fish kill" while cetaceans (whales and dolphins) and other marine mammals were not spotted.
Dong named Siemens as the preferred supplier to the project, using 91 6MW turbines. Race Bank is expected online in 2018.