The surname Bobbio is of clearly toponymic origin and is linked to various localities of northern Italy. According to E. De Felice, it is a surname peculiar to central-eastern Liguria and also to Piedmont, derived mainly from the place name Bobbio (province of Piacenza), in the Val Trebbia, an area historically connected with Liguria, both through the abbey of San Colombano and through its ecclesiastical organisation. For the Piedmontese sphere, he also notes the possible derivation from Bobbio Pellice (Turin).

Along the same lines, E. Rossoni confirms the toponymic origin, indicating several clusters of diffusion: between Pavia, Alessandria and Genoa (with greater concentration in Alessandria and Novi Ligure), another in the Turin area and a third in the Novara area. All these foci refer to different related place names, such as Bobbio Pellice or the Piani di Bobbio. He also documents the historical presence of the surname in the 16th–17th centuries, as in the case of the notary Gianbattista Bobius in Soncino.

Taken together, both interpretations agree in pointing to a multiple but coherent geographical origin, where the surname identifies people coming from localities called Bobbio or linked to that territory, with subsequent diffusion in various areas of northern Italy.