The authors agree that this surname derives from the personal name Gervasio, which continues the late Latin Gervasius, of probable Germanic origin, diffused by the cult of the saints Gervasius and Protasius, martyrs under the emperor Domitian and co-patrons of Milan.

E. Rossoni notes that in some cases the surname could derive not from the personal name but from homonymous place names, such as Palazzo San Gervasio, in the province of Potenza. Rossoni documents its transformation into a surname in the Cosenza area and in the Lecce area during the 17th century, and in the Sondrio area during the 18th century.

E. De Felice indicates that the surname has a sporadic presence in Italy and notes variants typical of the north-east: Gervasutti, Gervasùt, Vasolìn and Vasón, forms characteristic of Veneto. He also highlights that Gervasi and its variants with an initial C- are concentrated in southern Italy.