According to Thucydides, the city was founded in 1360 BC or 1031 BC and was inhabited by the Sicels circa the 7th century BC. It was probably from an early period a dependency of Syracuse. Modica was occupied by the Romans after the battle of the Egadi islands against the Carthaginians in the Punic Wars 241 BC, together with Syracuse and all the Sicily. Modica became one of the thirty-five decuman ("spontaneously submitted") cities of the island and was oppressed by the praetor Verres. It became an independent municipium, and apparently a place of some consequence. The city is also mentioned among the inland towns of the island both by Pliny and Ptolemy.

The south-east of Sicily and Modica (according to the German historian L. Hertling) was precociously Christianized, as the diocese of Syracuse boasts an apostolic foundation by St. Paul in 61 AD . In 535, the Byzantine general Belisarius expelled the Goths and established for Justinian I the government of the East-Roman Empire  and the already Greek-speaking population fixed their culture until the Latinization of the Normans in the 11th century. In 845, Modica was captured by the Arabs who referred to the city as Mudiqah. In 1091  the Normans, led by Roger of Hauteville, reconquered Sicily.

The County of Modica was a semi-independent feudal territory which existed within the Kingdom of Sicily from 1296 to 1812. Its capital was Modica, on the southern tip of the island, although the cities of Ragusa and Scicli housed some government offices for a period.

On 25 March 1296, King Frederick II of Aragon conceded the great County of Modica to Manfredi I Chiaramonte, which fought the Angevin and their king James and married Isabella Mosca, daughter of the rebel count Federico Mosca.The first dynasty of Counts obtained from the King lots of feuds in Agrigento, Caccamo, Licata and Palermo, where they built a beautiful palace called the Steri or Palazzo Chiaramonte; after being residence of the Viceroy and of the Holy Inquisition is now residence of Palermo University. It contains on its ceilings one of the most important pictorial cycles on wood of the Italian Middle Ages.

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At the death of king Frederick IV, Manfredi III Chiaramonte became viceroy and tried to defend the throne of Sicily supporting the illegitimate king Martin I. Unfortunately the city of Palermo fell and his governor Andrea Chiaramonte, son of the late Manfredi, 8th Count of Modica, was beheaded on July 1, 1392, by the new king Martin I of Aragon in front of his palace in the Marina Square of Modica.

The Cabreras

The new Count became Bernat Cabrera, a Spanish condottiero who actually conquered Sicily for the new Spanish king. The County of Modica was now bigger and stronger: it included the city of Scicli, Spaccaforno (today's Ispica), Ragusa, Chiaramonte Gulfi, Comiso, Giarratana, Monterosso Almo, Biscari and the castles of Dirillo and Cammarana. The Count had the right to export 3,112.68 tons of grain per year free of duties from one of his 7 ports, Pozzallo, where he built the beautiful Cabrera Tower.

Modica since 1296 was the capital city of a ‘state within a stateì, as  written in the Investiture  to Bernat Cabrera: Sicut ego in regno meo tu in comitato tuo ("You in your county as me in my kingdom"). The county had a Governor, its own Tribunals including the Tribunal of Second Instance, and a police force. The city part of the state were ruled by a municipal magistracy according to the Governor.

In the 15th and 16th centuries  the privatization of the land with the reformation of the Governor Bernaldo Del Nero gave the city the leading role in the south-east of Sicily. The lower part of Modica grew with churches, high-class palaces and monasteries, until the 1693 earthquake, that killed over   60,000 people in Sicily from Catania to Siracusa, and destroyed numerous buildings. The late Baroque of Val di Noto is the result of the reconstruction.

On March 5, 1607, Vittoria Colonna Enriquez-Cabrera, Countess of Modica, daughter of the Viceroy Marcantonio Duke of Tagliacozzo and wife of Ludovico III Enriquez-Cabrera, founded the new city of Vittoria, now the second most populous city in the province of Ragusa.

The title and the position of Count of Modica was held in succession by two other noble families, the Alvarez and finally the Fitz-Stuart. However by the time of the latter dynasties the title of Count was meaningless and carried little power, and Modica ruled on its own. This situation continued until the 18th century when Sicily was ruled by the Austrians, then in the late 18th and early 19th century as part of the  Kingdom of the Two Sicilies), and then finally after the Risorgimento it was unified with the rest of Italy in 1860.   Modica remained district capital until 1926, when it was included in the province of Ragusa.  In 2002 it became a UNESCO city, for its wealth of Baroque architecture..