Revolution Wind, then under the control of Deepwater Wind, was selected to secure grid capacity in the state's RfP in June.
Now Ørsted, which acquired Deepwater Wind in October, has signed the 20-year contract for output from 200MW of the project with local utilities Eversource and United Illuminating.
The developer said the completion of the deal means work on the project can "accelerate". Construction is planned for 2022, with a completion date of 2023.
Output from the remaining 400MW will be sold to utilties in Rhode Island, following that state's RfP earlier in the year.
At least $15 million was been pledged by Deepwater Wind to be invested in the Port of New London in the east of the state.
"We're ready to make major investments in our local workforce and in the Port of New London to ramp up this project," said Jeff Grybowski, co-CEO of Ørsted US Offshore Wind — the entity created after the acqusition of Deepwater Wind.