The two wind farms at Race Bank (580MW) and Dudgeon (560MW) in the Greater Wash could generate enough electricity to power around 730,000 homes.
The projects represent around £3bn of investment.
There is now 6.6GW of offshore wind power is now either operational, under construction or consented in UK waters.
However, an application for a third project at Docking Shoal, also off the Norfolk Coast, was refused due to the potential impact on seabirds in the area. Sandwich terns are specially protected by environmental legislation.
Race Bank is being developed by Centrica and the Dudgeon scheme is being taken forward by Warwick Energy. The rejected Docking Shoal scheme was also Centrica’s.
Energy minister Charles Hendry said: “The UK is racing ahead of the global field and these two new offshore wind farms underline this momentum. These two projects will not only bring us considerable amounts of clean energy, but significant investment and jobs too.
“We have also shown that we are mindful of other consequences, such as the impact on bird populations, in deciding that it would not be appropriate to consent all three applications.”