The turbines stand about 262m (860ft) tall and have a rotor diameter of 236m (775ft). Work to install the foundations began last year.
SPR says, when complete, East Anglia Three will produce 1.4 gigawatts (GW) of electricity, enough for more than 1.3 million homes.
It is aiming to have East Anglia Three operational in 2026.
Charlie Jordan, SPR chief executive, said: “This is a defining moment as we celebrate and accelerate the deployment of homegrown renewable energy at scale.
“East Anglia Three will be the biggest and most powerful offshore wind farm in our portfolio.
“That means billions of pounds invested in UK and global supply chains; thousands of jobs supported during construction; more than a hundred long-term roles created in the East of England; and greater energy security, with more clean power coming onto the grid than ever before.”
