The authors agree that the surname derives from the given name Giuliano, which continues the Latin cognomen Iulianus, itself formed on Iulius.

E. De Felice notes that Iulianus derives from Iulius, and that the surname shows regional variants: the Venetan form Zuliano or Zuliàn and the southern form Iuliano. He adds that some cases may derive not from a personal name but from place names, such as Giuliano in the province of Lecce, Giuliano di Roma in the province of Frosinone, Giuliano Teatino in the province of Chieti, Giuliana in the province of Palermo, Zugliàno in the provinces of Vicenza and Udine, and Zuiano in the province of Udine.

F. De Laurentiis specifies that the nominal base is Giulio, from the Latin Iuliu(m), from which the name Iulianum was derived with the suffix -anu(m). On the etymology of Iulius, he proposes —though without certainty— that it could represent an unattested adjective iouilos, with the sense "of Jupiter" (Iovis), or else simply indicate "he who was born in the month of July". He further notes that the surname may have been formed from the demonym Giuliano, with the sense "inhabitant of, or native of, Venezia Giulia", a historical region of north-eastern Italy.