Danish developer Dong Energy handed the Scottish-based subsea specialist the contract to clear the seabed for the installation of 35 array cables, eight kilometres off the UK's northeast coast.
ESS's boulder clearance system has been deployed from the Havila Jupiter vessel with remotely operated vehicle support. Clearing is expected to be completed by the end of this year's third quarter.
Westermost Rough will be made up of 35 Siemens 6MW turbines when it is commissioned in 2015.
Foundations at the development were installed in May and the substation was completed in June. Turbine installation is expected to begin this year.
Westermost Rough is jointly owned by Dong, Japanese corporation Marubeni and the UK's Green Investment Bank. The project represents the first time Siemens' new 6MW turbine will be used on a commercial project.
ESS has worked on the cabling system for the 219MW Humber Gateway project, also off the northeast coast.