The authors agree that this surname has as its base the patronymic name and nickname Catalano, meaning "inhabitant or native of Catalonia and, in a broader sense, of southern Spain". E. De Felice documents the Latin form Catalanus from the 11th century and, in Florence, the variant Catelanus in the 12th century. Both De Felice and F. De Laurentiis explain its diffusion by the intense migratory movement of Catalans towards Italy through the south of France between the 11th and 13th centuries, and by the maritime commercial relations between Barcelona and the Italian maritime republics in that same period.

F. Miranda broadens the ethnic origin by noting that the surname could derive from the Catalans, Aragonese and Valencians who arrived in Italy —especially in Sicily and the south— from the time of the Sicilian Vespers. Miranda adds two more remote hypotheses: that the nickname could go back to veterans of the legions of Pompey who had fought in Catalonia, or to Hebrews expelled from Spain.

G. P. Holmes notes that the surname could have originated directly from the medieval Latin name Catalanus or from nicknames linked to the geographical origin of the progenitor. De Felice adds that the variant Catalán is peculiar to the northeast of Italy, in the regions of Veneto, Friuli-Venezia Giulia and Trentino-Alto Adige, while Catelani corresponds to Tuscany. Taken together, the surname is present throughout Italy, with greater frequency in the south, particularly in Sicily, Campania, Calabria, Basilicata and Puglia.