The surname Zani (and related forms) is interpreted, according to the main scholars, from an anthroponymic origin linked to the name Giovanni. E. Rossoni notes that it derives from dialectal variations arisen from the loss of the initial syllable of the Latin name Johannes (Gianni), giving rise to forms such as Giani, Zani and Zanni, as well as their diminutives and augmentatives. These transformations are typical of northern Italy and reflect the phonetic evolution in the different dialects. The author also provides early historical documentation, such as the presence of the name Zani in a notarial register of the province of Sondrio in 1379, which evidences its antiquity.

For his part, F. De Laurentiis synthesises this origin by indicating that the surname derives from Zanni, one of the most widespread dialectal forms of Giovanni. This relationship reinforces the interpretation of Zani as part of a broad group of surnames derived from one of the most common personal names in the Italian tradition.

As a whole, the surname Zani reflects the transformation of Giovanni into multiple dialectal variants that, over time, became fixed as hereditary surnames, especially in northern Italy, preserving the trace of their common origin.