A religious ceremony is to be celebrated July 9, 2011, while the civil wedding is to take place the day before at the palace.
The couple announced their engagement last month.
Wittstock is a 32-year-old South African former youth worker and Olympic swimmer.
The prince, 52, is the son of the late Prince Rainier III, Louis Henri Maxence Bertrand Grimaldi, and the late Princess Grace, a one-time Hollywood screen icon. He also is a former Olympic bobsledder.
Prince Albert II succeeded his father, Prince Rainier III, as ruler of Monaco July 12, 2005.