E. De Stefani explains that the surname derives from the affectionate form Bert (Italian Berto), an abbreviated variant of Germanic names such as Adalberto, Alberto or Umberto, to which the Friulian suffix -on was added before its Italianisation as Bertoni. The Germanic root berhta meant "resplendent, radiant, illustrious", and gave rise to numerous compound names introduced to Italy mainly by the Lombards, which over time became surnames.

F. De Laurentiis presents it as a form derived from Bèrti, with wide presence in Tuscany, in Emilia-Romagna and in northeastern Italy, in the regions of Veneto, Friuli-Venezia Giulia and Trentino-Alto Adige.

De Stefani adds more precise geographical distribution data: the surname is spread across much of Italy, with presence documented from the beginning of the 18th century in the Carnia —a mountainous area of northern Friuli, in the province of Udine—, particularly in the localities of Enemonzo and Quinis, as well as Tricesimo and Nimis outside that area.