Siemens would deliver 171 7MW turbines to the site, located 120 kilometres off England's east coast.
The deal should be finalised after Dong makes a final investment decision, expected in the second half of next year, the developer said.
Dong's senior vice president for wind power, Mats Vikholm, said: "The decision by Siemens to open new production facilities in Hull on the British east coast is a key factor in bringing down the cost of wind turbines for this project."
Recent correspondence uncovered by Windpower Monthly between Siemens and the UK government showed there could be some form of local sourcing policy put in place.
Dong acquired the project from the Smart Wind consortium, which it was part of, in February.
Siemens was recently named preferred supplier for Dong's 330MW Walney Extension phase two project, also set to use the 7MW.
Also today, Siemens confirmed an order from Dong to supply 91 of its 6MW turbine to the 580MW Race Bank project. The agreement includes five years' servicing. Last week, Dong made a final investment decision for the Race Bank project in the North Sea.