Dong has paid Centrica £40 million in cash to acquire a 50% share of the project. £15 million will be paid up front. The balance will be paid when they gain consent for a project in the zone and both agree to proceed.
Last week's announcement from Dong that it is to invest DKK 10 billion (€1.34 billion) a year for the next seven years, developing its offshore project portfolio.
Speaking about the Irish Sea announcement, Dong's acting CEO Carsten Krogsgaard Thomsen said: "This marks DONG Energy's second entry into a Round 3 project and Centrica is a natural partner for us as we already have a good working relationship with them from previous projects.
"It is a strategic addition to our long-term pipeline of projects which contributes to the industrialisation of the offshore wind business and bringing down costs."
The deal gives Dong a further foothold in the UK's 33GW Round 3 offshore programme. In January 2010, when the Round 3 results were announced, many industry observers were surprised Dong had failed to win a project.
This was changed late last year when Dong acquired part of the 4GW Horsea zone, on the east coast of England, from Mainstream Renewables.