The authors agree in noting that the surname Marullo probably derives from the Latin merula (turdus merula), that is, the blackbird. G. P. Holmes adds that this hypothesis is supported by some genealogists of the noble Messinese family of the Marullo di Condojanni, who considered themselves descendants of the Roman consul Lucius Cornelius Merula.

F. Miranda further proposes two alternative etymologies: the Sicilian term mirudda, midudda or miduddra, with the meaning "brain, mind, intelligence", and the modern Greek marouli, which means "lettuce". Miranda also notes that Marullo was the surname of a well-to-do family of Constantinople.

According to Miranda, the surname has its most substantial core in Sicily, with a presence concentrated in the Catania, Palermo, Messina, Agrigento, Enna and Syracuse areas. It extends likewise across Puglia, Lombardy, Campania, Lazio, Calabria and Piedmont, and appears in lesser areas of Liguria, Abruzzo, Emilia-Romagna and Tuscany.