The authors agree that this surname derives from the medieval personal name Chiriaco, an adaptation of the Greek Kyriakós (κυριακός), whose root is Kyrios ("Lord") with the adjectival suffix -akos, with the meaning of "of the Lord" or "dedicated to God". It is the Greek equivalent of the name Domingo, and reflects the religious onomastics of Byzantine tradition.

E. Rossoni distinguishes two variants: Chiriaco, peculiar to Calabria —especially in the Catanzaro and Crotone areas and in the locality of Maida—, and Chiriacò, characteristic of the Salento area —that is, the southernmost zone of the region of Puglia, in southern Italy—, with presence in Sternatia, Lecce, Cutrofiano and Brindisi. By its geographical distribution, Rossoni notes a probable Albanian or Greek ancestry, in particular in the Reggio Calabria area and in the Salento.

G. Rohlfs specifies that in Greece it still survives as a surname under the form Kyriakòs, and that in the Salento it is documented in Corigliano, Cutrofiano, Lecce and Sternàtia. V. Blunda adds that the name motivated the surname as a Byzantine personal name applied to the one who was consecrated to the religious sphere.