From the ancient French first name Richard.

The authors agree that this surname derives from the medieval given name Ricciardus or Riccardus, a Latinized form of the Germanic Richard, composed of rik- ("powerful, lord") and hard- ("strong, brave"). Its original sense can be interpreted as "the strong one in power" or "the bold ruler." It is considered that this personal name, diffused in Italy first by the Franks and later by the Normans and Angevins, was transformed into a patronymic surname during the Middle Ages, indicating "son or descendant of Riccardo / Ricciardo."

E. Rossoni notes that the name is documented in a writing of Leon Battista Alberti of the 15th century, and that Ricciardo is specific to the Brolo and Ficarra area, in the Messina area. For his part, F. Miranda indicates that Ricciardi has its greatest concentration in Campania, especially in the Caserta, Naples and Salerno areas, with a presence also in Apulia, Sicily, Basilicata, Lazio, Lombardy, Tuscany, Piedmont, Liguria and Emilia-Romagna. In Sicily it appears in all the provinces, with a particular presence in the Messina area.

It is considered that the main variants —Riccardi, Ricciardi and Rizzardi— respond to regional phonetic and dialect adaptations of the same patronymic surname, without difference of meaning. In Piedmont, forms such as Ricchiardi and Richiardone arose, by phonetic adaptation of the French Richard. The various derivatives —Ricciardello, Ricciardone, Riccardini, Riccardis, among others— were formed through diminutive, affective or patronymic suffixes proper to each region, characteristic of the formation of surnames between the 13th and 15th centuries.