The authors agree that the surname was formed from the name of Germanic origin Azzo or Azzone, documented as early as the 6th century.

E. De Felice specifies that, from the 8th century onwards, the name appears frequently in the forms Acio and Açó, Atho (pronounced àzzo), Azo and Atzo, and Azzóne (which is originally the oblique case of the Germanic declension Latinised in -o, -one). He notes that the Germanic personal name, of Lombard tradition by the area and the antiquity of the documentation, is an abbreviated hypocoristic of names compounded with the first element Ad- (from atha- and athala-, "noble, nobility of stock"), such as Adalberto, Ademaro, Adinolfo or Adolfo, formed with the suffix -zo.

De Felice adds that the type Azzano and D'Azzano, Dazzano, may also represent, in the Veneto and in Friuli-Venezia Giulia, the place name Azzano (in the provinces of Verona and Udine) and Azzano Decimo (in the province of Udine). He documents it as early as the 6th century in Parenzo, in Istria, in an inscription of a barbarian cemetery. He notes that the surname is widespread in the north —more frequently in Lombardy and in Emilia-Romagna— and in Tuscany.

E. Rossoni suggests that all the forms derive, directly or through affectionate or augmentative variants, from the medieval name Atto or Azzo, or from its diminutive form Azzolo. Among the historical figures he mentions Azzo d'Este, Azzo da Correggio (Parma, 1303), marquis of Correggio and lord of Parma, and Azzo di Malaspina in the second half of the 14th century. He documents the surname in the Bergamo area at the beginning of the 17th century.

F. De Laurentiis agrees on the Germanic origin of the name Azzo and Azzone, documented from the 6th century, and links it later to the Este lineage and to the de' Contrari family (holder of the patronage of Santa Maria Maddalena). He adds that, in the Veneto and in Friuli-Venezia Giulia, the surname may also represent the place names Azzano (in the provinces of Verona and Udine) and Azzano Decimo (in the province of Udine).