E. De Felice notes that this surname was formed from the toponymic type Garbagnate, frequent in northern Italy: Garbagnate Milanese, in the Milan area; Garbagnate Monastero and Garbagnate Rota, in the Como area; and Garbagnate Novarese, in the Novara area. It is, therefore, a surname of clearly toponymic origin, linked to localities of upper Lombardy.

E. Rossoni agrees on the toponymic origin and mentions specifically Garbagnate Milanese and Garbagnate Monastero —this last currently in the province of Lecco— as the most probable localities of reference. Rossoni also specifies that the surname is concentrated in zones of the north of Milan: localities such as Lazzate, Nerviano, Monza and Lentate sul Seveso, with presence also in Cermenate, in the Como area.