E. Rossoni proposes two hypotheses on the origin of this surname: it could derive from dialectal Italianized forms of the German name Franz (equivalent to Francesco), or from dialectal alterations of the word Francia or Franza, which would indicate that the founders of the lineage came from France or that they maintained frequent commercial relations with that country. Rossoni notes that Franzo, very rare, is peculiar to the Venice area; that Franzoi has an important presence in Trentino and another in the Venice area; and that Franzoia, very scarce, presents a small zone in the Alessandria area and another between the lower Belluno and the Treviso area.

F. De Laurentiis considers that the surname is a variant of Francia, which coincides partially with the second hypothesis posited by Rossoni.