The authors agree that this surname refers to a trade or function linked to work with horses. F. Miranda considers it a variant of Cavallo, derived from the Late Latin caballarius, with the meanings of "keeper of horses", "horse dealer", "head of a caravan of horses" or "messenger on horseback". Miranda also rules out the hypothesis of a toponymic origin, noting that there is no city called Cavallaro, only small localities that contain that word in their name.

G. P. Holmes links it to medieval nicknames related to trades, occupations or ranks associated with the horse, in the sense of "keeper, dealer or driver" of these animals. For his part, V. Blunda highlights its Sicilian rooting and derives it from the dialectal word cavaddàru, "groom, keeper of horses", a function of relevance in the agrarian economy of Sicily. Blunda also notes that this surname forms a lexical pair with Cavaleri ("soldier on horseback"), both belonging to the same semantic field.

Miranda indicates that the surname is spread in all the regions of Italy, with especially notable presence in Sicily, Veneto, Lombardy, Campania, Piedmont, Calabria and Lazio. In Sicily it is concentrated in the Catania, Messina, Palermo, Syracuse areas and in the Enna area.