E. Rossoni notes that the surname can derive from nicknames based on the term castagnola, meaning "small chestnut", or, more probably, from names of homonymous localities present in numerous areas of Italy. Among them he mentions Castagnola di Franconalto, in the Alessandria area, and Castagnola delle Ferriere, in the Piacenza area. The surname presents historical documentation in various areas: the Pavia area, the Alessandria area, the Piacenza area and the Genoa area, with an old presence also in Naples recorded from the 16th century.

V. Blunda approaches the analysis from the Sicilian perspective and proposes that the surname originated as a nickname from the dialectal word castagnola. According to this author, it could have been applied to a person of slight build and dark complexion, in a visual metaphor derived from the brown shiny fruit of the chestnut tree, or be linked to the trade of the one who gathered or sold chestnuts. Blunda places the surname in the context of the mountainous areas of Sicily, such as the Nebrodi and the area of Etna, where the chestnut tree had a central role in the local economy.