Iberdrola-subsidiary SPR has arranged £2.5bn (€3.2bn) in financing to build the site, located 42km off the UK's east coast.
The site would be Iberdrola's second offshore wind project in the UK, following its involvement in the West of Duddon Sands offshore wind project in the Irish Sea, which was completed in 2014.
Siemens was named preferred supplier for the site in June 2015, dependent on a final investment decision. The German manufacturer is set to supply 102 7MW turbines to the project.
Turbine installation is set to begin in 2019, with project commissioning due in 2020.
East Anglia One was due to have a 1.2GW capacity, but was cut in size, because of restrictions on government support.
The project was one of only two offshore sites to be awarded a Contract for Difference subsidy by the UK government towards the end of February 2015.
In the auction process, SPR bid a strike price of £119.89/MWh to be paid over the 15-year contract.
ScottishPower said it was aiming to spend half the €2.5bn investment in the UK supply chain – ahead of hints future UK offshore projects may be required to do similar.
"Offshore wind has proven itself as a technology that works, and the more offshore wind capacity we have in the UK, the more secure our energy supplies will be. East Anglia has some of the best conditions anywhere in the world for the development of offshore wind, and we are fully committed to the region, with future developments already in the pipeline," said project director Charlie Jordan.
The 714MW East Anglia One project will be the first site in the planned 7.2GW East Anglia round three zone being developed by SPR and Swedish utility Vattenfall.
SPR is planning four sites in the southern half of the zone, while Vattenfall is responsible for sites in the northern half, following a split of their joint venture in August.