E. De Felice notes that the surname has as its base the name Rocco, documented in Italy from the 9th century but consolidated only in the 15th century with the diffusion of the cult of Saint Roch. He adds that the Piedmontese surnames are Roccati, Rocchetti and Rocchietti, and that it is diffused throughout Italy, with a high frequency in the Naples area.

A. Bongioanni suggests that the name comes possibly from the Old Norse hrokr ("a man of tall stature") and reached Italy through the French Roc. He recalls that Saint Roch, a 14th-century pilgrim from Montpellier, is venerated as the protector of those sick with plague (16 August).

V. Blunda, for the Sicilian variant, derives it from the Germanic personal name Hroc, linked to the root hroc ("rock, fortress") in its simple form.

Blunda also recalls that Saint Roch of Montpellier (c. 1295–1327), a French pilgrim, dedicated his life to the care of those sick with plague during one of the epidemics that ravaged Europe. He himself contracted the disease and was venerated as a protector against plagues throughout medieval Christendom. His characteristic iconography —with the pilgrim's staff, the visible wound on the thigh and the faithful dog that brought him bread— spread widely in Late Medieval and Renaissance European devotional painting.