The authors agree that this surname derives from the given name of Germanic origin and Lombard tradition Landulfus, documented from the 8th century. E. De Felice specifies that it is formed from the elements landa ("territory, country") and wulfa ("wolf", and "fighter bold and strong as a wolf"), with the original meaning "strong and bold in his own country". V. Blunda agrees on the components, though he renders the whole as "wolf of the land" or "wolf of the territory".

E. Rossoni supplies concrete historical documentation: the name Landulfus appears in the life of Saint Thomas Aquinas, in a deed of 1231 concerning an abbot of Montecassino. Rossoni also records traces of the surname in Solofra, in the Avellino area, from the 11th century, and notes that in the 14th century the Landolfi were enrolled in the register of notables of that city. Blunda, for his part, mentions Landulf I of Capua (c. 840–879), a Lombard prince of southern Italy, as a historical figure associated with the name.

As for geographical distribution, Rossoni notes that Landolfi is typical of the region of Campania; Landolfo has areas of presence in the Naples area and in the Lecce area; and Landulfo, extremely rare, appears to be concentrated in the Salerno area. De Felice indicates that the surname predominates in Naples. Blunda records it also in Sicily.