The authors agree that this surname derives from the place name Castrogiovanni, the old name of the city of Enna, in Sicily.

F. Miranda offers a detailed etymological development. The name of the city has its origin in a term of the Sicanian language, Ennaan, which the Greeks Hellenised as Henna and the Romans recorded as Henna or Hennae. The Arabs transformed it into Qars Yanna, "fortress of Enna"; the Normans Latinised it as Castrum Joannes, from which derive the Sicilian Castruggiuvanni and the Italian Castrogiovanni. In 1927 the city recovered the name of Enna.

Miranda notes that the surname is of entirely Sicilian origin and spread throughout the island, with presence especially in the Palermo, Catania, Enna, Caltanissetta, Agrigento, Messina and Syracuse areas. E. Rossoni agrees in linking the surname to the place name Castrogiovanni and circumscribes its origin to Sicily, with particular reference to the Enna area.