The authors agree that the surname derives from the medieval personal name Lanzo. E. Rossoni documents this name in a Cartula commutationis of the year 1039 in Bergamo, where a certain Lanzo is mentioned in the Latin form Lanzonis. Rossoni also notes that the surname could have originated from place names of the same form: Lanzo di Martina Franca, in the Taranto area; Lanzo d'Intelvi, in the Como area; and Lanzo Torinese, in the Turin area.

V. Blunda specifies that the personal name Lanzo is a hypocoristic form of the Germanic root landa, meaning "land, territory", and that it shows a consonant palatalization characteristic of northern Italy. Blunda further warns that the popular reading associating the surname with the term lanzichenecco —the German mercenary of the 15th and 16th centuries— is a late crossed etymology: that military term comes from the German Landsknecht, coined in the time of Maximilian I, long after the origin of the medieval personal name.

As for its distribution, Rossoni identifies specific areas of presence for the various variants. Lanzon is of very scarce occurrence. Lanzone has a main core in Apulia and in the Campobasso area, with lesser presences in the Cosenza, Rome, Turin, Cuneo, Genoa and Milan areas. Lanzoni is very widespread in Lombardy and Emilia-Romagna, with an extended presence throughout northern Italy. Blunda places the surname in its base form mainly in Sicily.