FRANKFURT—Siemens AG received an order on Wednesday to build gas and wind power plants in Egypt valued at €8 billion ($9 billion), which the German company described as the largest single order in its history.

Siemens signed contracts for the order, which will boost Egypt’s power production, with Egyptian President Abdel Fattah Al-Sisi on Wednesday at Germany’s Federal Ministry for Economic Affairs and Energy. Siemens will deliver three ready-to-use gas-steam power plants with a capacity of 4.8 gigawatts each. The plants,...