The scholars consulted agree that Pellegrini is a surname of anthroponymic and nickname origin, derived from the term pellegrino — itself from the Latin peregrinus, meaning "outsider" or "foreigner" — which was used from the Middle Ages onward to designate those who undertook pilgrimages to sacred sites of Christianity, including Rome and Santiago de Compostela.

E. De Felice and F. De Laurentiis add that in some cases the surname may also derive from the personal name Pellegrino, or from place names such as Pellegrino or San Pellegrino, introducing a possible toponymic dimension alongside the more common nickname origin. E. De Stefani, for his part, emphasizes the role of religious devotion and of ecclesiastical figures who bore this name, noting that their influence favored its spread as a personal name and its subsequent transformation into a hereditary surname.

The surname is attested with high frequency across Italy. Altered and derived forms predominate in Emilia-Romagna and Tuscany, while the variant Pellerini is limited to the northwestern part of the country. It is also recorded simply as a development from the common noun pellegrino, meaning "pilgrim."