The consulted authors agree that the surname has its origin in an ethnic adjective: scotus, a medieval Latin term that designated the Scotsman, in a similar way to how franciscus first meant "Frank" and later "Frenchman." This appellative base was used initially as a nickname and over time transformed into a surname.

Early historical documentation is recorded in the Acts of the Municipality of Milan, where the forms Scoto, de Scoto and Scotus appear accompanied by numerous medieval given names, which evidences a consolidated presence of the surname in that city.

E. Rossoni specifies that the variant Scotti is proper to Lombardy, with a possible secondary line in the Naples area, and notes that the Scotti are documented from the 12th century as a noble family in the Piacenza area. The variant Scotto, of Ligurian origin, presents secondary lines in the Grosseto area and in the Naples area. Rossoni also points as an alternative possibility to the derivation by aphaeresis of medieval names such as Brasco, Brunellesco, Fiesco or Fosco, or else of ethnic indicators such as tedesco.