The authors agree that the surname originates in a name of Germanic root, although they differ in their interpretation. E. Rossoni notes that all the variants derive from the Lombard name Guisulf, Latinized as Ghisulfus, documented in a deed of the year 854 in Milan and, centuries later, in the Codex Diplomaticus Papiensis, in a deed of division of March 1234 in Pieve Porto Morone. F. De Laurentiis agrees on the Germanic origin and proposes that the base name, Ghisolfo, means "will of a bear". V. Blunda, by contrast, analyses the surname as a Germanic compound formed by gis ("arrow" or "dart") and vulfa ("wolf"), with the sense "wolf of the arrow", and stresses that the wolf was a central totemic animal in Germanic culture, associated with warrior ferocity and present as the second element in numerous European personal names such as Adolfo, Rodolfo or Arnolfo.

According to Rossoni, the surname is most widespread in Lombardy, especially in the Cremona area and in Milan, and also in Piedmont, around Tortona, Turin and Cuneo. The variant Gisolfi has a significant presence in the region of Campania, in the Salerno area, as well as isolated clusters in Naples and in Rignano Garganico. The form Ghisolfo, very scarce, appears in the Savona area, as does the almost non-existent Gisulfo. Blunda, for his part, links the surname to Sicily.