The first human settlement in the area dates back to the early Bronze Age (18th-15th century BC) of the Castelluccio civilization, but traces of the Finocchito Civilization from the 8th-7th century BC are also present. In the 5th century BC, Ducezio, the King of the Siculi, in anticipation of war against the Greek invaders, would have moved Neai (which he was born in), of uncertain location, from the Mendola hill, in the Alveria plateau, a singular heart-shaped mountain, surrounded by deep ravines that made it unassailable, except for a narrow isthmus that was fortified. Recent studies tend to exclude Ducezio’s citizenship in Noto and, therefore, the relocation of Noto. It is, however, certain that Mount Alveria was inhabited since prehistoric times and later became the site of various Siculian communities starting from the 9th century BC. The gymnasium, heroa, vast pit necropolises, temples, and theaters recorded indicate the high regard the Siculian city enjoyed from the Greek conquerors, from whom it assimilated their cults and customs.

In 263 BC, Neaiton (Latinized as Neetum, Netum) was assigned by Rome to Hiero II, the tyrant of Syracuse, but it enjoyed a certain autonomy, perhaps due to the Latin origin of the Siculi. This autonomy later (seemingly during the Second Punic War) resulted in a federative pact with Rome (Civitas foederata), which made it equal to the other two federated cities of Sicily: Messina and Taormina. The people of Noto always valued their position as allies of the Romans and, in 70 BC, as Cicero reports, they were among the fiercest accusers in the trial against the propraetor Gaius Verres, who had unjustly demanded the payment of a tithe from them. Even in imperial times, Rome continued to favor Noto, granting it the status of municipium and exempting it from paying the stipendium. Very few Roman-era remnants survive, while the later antiquity and Early Middle Ages remain largely obscure until the 9th century. However, there are scattered rock-cut neighborhoods on Mount Alveria, probably Byzantine, a Christian hypogeum of considerable size (Grotta delle 100 bocche), and a Jewish catacomb (G

Netum surrendered in 864 to the besieging forces commanded by Cafagh Ibn Sofian. Shortly afterward, it managed to shake off the yoke but fell again two years later. In the 10th century, the island was divided into three Valleys, with Noto being appointed to one of them. The invaders stimulated agriculture and commerce, planted vast citrus groves, and introduced the silk industry.