Under the contract worth more than €100m, Bilfinger will install 72 foundations at the project site 90km west of Sylt, where water depths are about 34m.
The wind farm is being jointly developed by Vattenfall and the city of Munich public utility Stadtwerke München.
Work under the contract is expected to be completed by February 2016.
Bilfinger executive board member Joachim Enenkel said: "The order will be carried out by our newly-formed offshore systems and grids division, in which we have brought together our marine engineering and grid construction activities within the power business segment."
Bilfinger is using a sound reduction system, Hydro Sound Damper, to reduce underwater noise pollution that could affect marine fauna in the construction phase.
Expected to generate 1.4TWh of renewable electricity, the project will have an investment of €1.2bn and Vatenfall will own 51% stake.
