The surname Bonanno is of anthroponymic origin and falls within the tradition of medieval auspicious names. According to E. De Felice, it derives from the name Bonanno, documented as early as the 13th century (for example, in Florence in 1260 as Bonannus), and can be interpreted as "[may it be] a good year", in reference to the birth of a child. He also notes that, in some cases, it could be linked with the base Bòno, reinforcing its positive sense.

From the point of view of diffusion, E. De Felice indicates that the surname is present throughout Italy, although it reaches its greatest frequency in Sicily, which suggests a strong rooting in that region.

For his part, E. Rossoni agrees on the auspicious character of the name, proposing its derivation from the Latin Bonusannus ("good year"), and adds a historical dimension by noting a possible Pisan origin of the lineage. He also documents the early presence of the surname in Sicily, especially in Caltagirone in the 13th century, where Giangiacomo Bonanno appears, promoted to grand chancellor of the kingdom by Frederick II.

Taken together, both interpretations agree in pointing to an auspicious origin linked to the idea of prosperity and good destiny, with an early consolidation in Sicily and a later diffusion in the rest of Italy.