The authors agree that Maffei is a surname of broad distribution in Italy, with a presence in the north as well as in the centre and the south of the country. F. Miranda notes that it is found in more than 800 comuni across every Italian region, with the greatest concentration in Tuscany, Lombardy, Trentino-Alto Adige and Piedmont, but also in Campania, Puglia, Emilia-Romagna and Lazio. In Sicily it appears in several provinces: in the Messina, Catania, Agrigento, Syracuse, Palermo and Enna areas.

As for the origin, Miranda explains that it is a patronymic surname —that is, derived from the father's name— with the meaning "the Maffei, the sons of Maffeo". Maffeo is a variant of the name Matteo, of Hebrew root, arisen from a different adaptation of the Greek Mathaios (Ματθαῖος); the substitution of the double tt by a double f is explained as a different reading of the Greek th. E. Rossoni agrees that the surname derives from the medieval Italian name Maffeo, and adds that the Maffei family has a long documented historical tradition, with notable figures linked to the Bergamo area and to the Republic of Genoa.