The authors agree that this surname derives from the transformation into a surname of the name of Germanic origin Carlo. That name is documented in Italy from the middle of the 8th century, in its Latinised forms Carolus, Carlus and Carlonus, but it became established between the 10th and 11th centuries through the direct influence of the Frankish name Karl and the prestige of Charlemagne. The Frankish name Karl comes from the Germanic karla-, which designated the "man of free condition" and, among the Franks, the "master of the palace" and later "high official of the court".

E. De Felice notes that the surname has pan-Italian reach in its main forms and its variants. Càroli is frequent in Emilia; the forms with the prefix De predominate in southern Italy and also in the Trento area; Di Carlo is mainly Sicilian; Carlovich is peculiar to Friuli-Venezia Giulia; Carlesso and the apocopated forms are mainly from the Veneto. The surname also includes variants such as Carlétto and Carlino, derived from the same base name.