E. De Felice notes that this surname was formed from aphaeretic hypocoristics —that is, forms reduced through the loss of the initial syllable— of surnames such as Bartolotto, Bartolone, Bartolossoo and Bartolusso, and more rarely of Bertolotto, Bertolone and related forms. These in turn derive from the name Bartolo or Bortolo, a hypocoristic of Bartolomeo, or else from Berto, a hypocoristic of Germanic names with that element.

E. Rossoni, on the other hand, proposes a more direct explanation: the surname would derive from the loss of the initial syllable of Bertolotti or Bertolotto. According to Rossoni, Tolotti is typically Lombard, with a presence also in the Trento area, while Tolotto is concentrated in the Treviso area, with a probable original stem in the Verona area.