Located offshore from the Suffolk coast, the facility will be part of a 3.3GW macro-complex called the East Anglia Hub, which will involve a €7.7bn ($7.9bn) investment.
The wind power plant will generate enough electricity to meet the power demands of 1.3 million homes and support the UK Government’s target to install 50GW of offshore wind capacity by 2030.
ScottishPower Renewables East Anglia Hub offshore managing director Ross Ovens said: “Net-zero climate change ambitions, energy security and the rising cost of living all point to the need for speed in delivering a greener, more self-sufficient future.
“Starting construction on EA THREE takes us one step closer to that reality and it’s great to see that happen so soon after the project’s success in Allocation Round Four.
“It’s a really exciting time for us and for the East of England.”
For the EA III project, ScottishPower Renewables will initially focus on building the onshore converter station at Bramford in Suffolk.
Siemens Energy High-Voltage Grids vice-president Mark Pilling said: “Working in a consortium with Aker Solutions, we’re committed to delivering safe, sustainable, efficient solutions for the UK market.
“East Anglia III will see us work with our partners on creating the green electricity infrastructure for an offshore wind farm that will have a 1,400MW capacity, and with it the potential to power 1.3 million homes.
“The project represents a significant step towards delivering on the UK’s energy transition and progressing to a net zero future.”