Princess Latifa Bin Fahd bin Abdulaziz Al Saud, who is 54 and a daughter of former king Fahd, bought the 18,800-square-metre (202,362-square-foot) estate from the wealthy Nordmann family that co-owns upscale department store chain Manor and the maker of Lacoste clothing.
The purchase price for the property, which once belonged to Gustave Ador, who served as Swiss president early in the 20th century, is the second-highest on record in the city.
The daughter of Kazakhstan President Nursultan Nazarbayev, Dinara Kulibayeva, holds the current record after she bought a property on the posh southern shores of Lake Geneva in 2009 for 74.7 million francs.
Al Saud, who like Kulibayeva has settled nearby in the municipality of Cologny, has committed to "preserving the heritage", the Tribune de Genève daily reported.
The villa on the estate, known as Hauterive, is protected along with other properties overlooking Lake Geneva.
"All the guarantees were given by the purchaser with regard to preserving this heritage," Bernard Favre, spokesman from the local urbanism department, is quoted as saying by the Tribune.
Outlying buildings on the estate are set to be converted, the newspaper said.
Al Saud joins a number of other Saudi royals who already live in luxurious settings in the canton of Geneva.