Dong UK chairman Brent Cheshire said repeatedly using Atkins allowed for standardising the design, thereby reducing costs of the project.
Hornsea 1 is located 120 kilometres off the UK's east cost and is due online in 2020. It is part of the 4GW Hornsea Zone.
In February, Dong acquired all of Hornsea 1 from the Smart Wind consortium consisting of Mainstream Renewable Power and Siemens. Dong previously owned a 33% stake in the development. The UK government gave its consent for the project in December.