E. Rossoni classifies Di Blasi as a southern patronymic surname with maximum concentration in Sicily and clusters also in Calabria and Campania. The variant Di Blasio is peculiar to the strip that comprises Abruzzo, Molise, Lazio and Campania, while De Blasi presents independent clusters of origin (ceppi) between the Palermo and Trapani areas, in the Salento area —that is, the southernmost zone of the region of Puglia— and in the Naples and Avellino areas.

From the etymological point of view, the authors agree that the surname is a patronymic form with the particle di ("son of") followed by the name Blasi, derived from the Latin cognomen Blaesus —meaning "stammering, stuttering"— or from the medieval Christian name Blasius, Italianized as Biagio. F. De Laurentiis specifies that the Latin base is the adjective blaesus, "who has an entangled tongue".

Rossoni notes that the name spread widely in medieval Christian onomastics thanks to the cult of Saint Blaise, bishop and martyr of Sebaste (Armenia, 4th century), the protector patron of throats, venerated throughout Italy with popular traditions linked to the blessing of throats on 3 February. Di Blasi belongs to the onomastic group of surnames derived from that name.