The surname Piacenza is of mainly toponymic origin and derives from the name of the city of Piacenza and from its demonym Piacentino. On this point E. De Felice, A. Bongioanni and E. Rossoni agree, noting that the surname was formed to indicate the geographic origin of the line, following a process usual in Italian onomastics.

E. De Felice and A. Bongioanni add that, in some particular cases in Piedmont, the surname could have an alternative origin, deriving from a feminine personal name with the meaning of 'pleasant' or 'agreeable'. Along the same lines, E. Rossoni confirms the predominant toponymic origin and further notes that in certain cases it may be linked with families of Hebrew origin, which broadens its historical context within the formation of the surname.