According to tradition, ancient Halaesa was founded in 403 BC, by Archonides of Herbita. Diodorus Siculus, a first-century BC Sicilian historian from ancient Agyrium provides the following account:
Archonides, the leader of Herbite, after the citizen-body of the Herbitaeans had concluded peace with Dionysius, determined to found a city. For he had not only many mercenaries but also a mixed throng who had streamed into the city in connection with the war against Dionysius; and many of the destitute among the Herbitaeans had promised him to join in the colony. Consequently, taking the multitude of refugees, he occupied a hill lying eight stades from the sea, on which he founded the city of Halaesa; and since there were other cities of Sicily with the same name, he called it Halaesa Archonidion after himself. When, in later times, the city grew greatly both because of the trade by sea and because the Romans exempted it from tribute, the Halaesans denied their kinship with the Herbitaeans, holding it a disgrace to be deemed colonists of an inferior city. Nevertheless, up to the present time numerous ties of relationships are to be found among both peoples, and they administer their sacrifices at the Temple of Apollo with the same routine. But there are those who state that Halaesa was founded by the Carthaginians at the time when Himilcon concluded his peace with Dionysius. (Diodorus Siculus 14.16.1-4)
Again according to Diodorus Siculus (23.4.1) Halaesa was the first Sicilian city to go over to Rome, in 263 BC, in the opening phases of the First Punic War (264-241 BC). This action, together with the city's key position on the north coast for trade (noted by Diodorus in the passage above), may explain Halaesa's privileged tax status under the Roman Republic, noted by Diodorus and recorded also, in 70 BC, by Cicero (Against Verres, 2.3.13). The city was exempt from the regular 10% grain tax exacted on harvests of most Sicilian cities' territory at this time. Cicero twice emphasizes Halaesa’s role as a port (Verr. 2.185, 3.192).
During a period of internal dispute among the citizens, Halaesa received laws on its internal self-regulation (leges de senatu cooptandu) at its own request from the Roman Senate - the arbitration and legislation was undertaken by the praetor in charge of the extortion court at Rome in 95 BC, Gaius Claudius Pulcher (Verr. 2.122). The city was one of many victims of the extortion undertaken by the notorious governor of Sicily between 73 and 71 BC Gaius Verres. According to Cicero, a certain Dio of Halaesa was Verres' very first victim in 73 (Verr. 2.2.19), robbed of the enormous sum of 1,100,000 sesterces. Marcus Tullius Cicero and his cousin visited the city in 70 BC, attending its senatus (Verr. 3.170), during their collection of evidence for Cicero's prosecution of Verres later that same year.
There is no clear evidence for what happened to Halaesa during the Roman civil wars of the 40s and 30s BC (many Sicilian cities suffered in the conflict between Sextus Pompeius and Octavian between 42 and 36 BC). However, indirect evidence from a series of inscriptions (ISic0800, ISic1175, ISic1176, ISic3571) suggests that the city safely navigated its way through the events, as at least one elite family (that of Lapiron) can be seen to be flourishing both before and after the period.
Under the first emperor, Augustus, the city gained the status of a Latin municipium, attested by the evidence of inscriptions (ISic0582) and coins (ISicNum0013) from the city.