The scholars consulted agree that this surname — together with its variants Paci, Pacione, and Pacioni — derives from the medieval auspicious given name Pace, itself from the Latin pax, pacis, meaning "peace." It is a pan-Italian surname, present in all regions of the country.

F. Miranda adds a dimension of particular interest: the name Pace was widely used from ancient times in Italian Jewish communities, which helps explain its broad diffusion. Jewish speakers adopted it as a translation of the Hebrew Shelomon or Shlomo (Italian Salomone), adapting it to the language of the country in which they lived. The name could function as a gratulatory expression ("born in a time of peace, who brings peace to the family") or as an auspicious wish ("may he have peace").

E. Rossoni details the geographical distribution of the variants: Paci is found in Romagna, Tuscany, the Marche, Umbria, Lazio, and in southern Sicily; Pacione appears in two distinct areas, one centered on L'Aquila, Rome, and Frosinone, and another in the area of Bari; Pacioni is concentrated between the areas of Macerata and Ascoli Piceno, in the Marche, and in Lazio.

G. P. Holmes proposes an alternative etymology: the surname may instead derive from the place name Pace del Mela, a municipality in the area of Messina, in Sicily.