The history of Petacciato is very ancient, but at the same time of uncertain origin, as there is partially dubious documentation. In pre-Roman times it was occupied by the Frentani, a people of uncertain origin. In fact, according to some historians these descended from the Samnites, for others, however, from the Liburnians, the Sabines or the Etruscans. Its names have also been multiple: Petazio, of Greco-Roman origin, means wide-brimmed hat, Potare, which means "to drink in abundance", probably due to the presence of numerous springs in its territory, as well as Betavium, "Petacciata" , "Pitacciato" etc.
The territory of Petacciato has always been disputed by various peoples and bandits. It suffered attacks from the Goths (5th century), the Byzantines (6th century), the Lombards (7th century).
The coastal center has been destroyed several times by earthquakes; those that occurred in the years 1117, 1125, 1456 are worth mentioning. The latter, in particular, on the night between 4 and 5 December, caused a terrible destruction of the town with the consequent death of numerous inhabitants. A few years of poverty and abandonment of the country followed.
In 1463 Petacciato was again razed to the ground by the Angevins, in battle against the Aragonese who Petacciato, together with Guglionesi, a neighboring town, had strenuously defended. Only towards the middle of the 16th century did Petacciato experience moments of prosperity again. In fact, there were settlements of Slavic people who guaranteed the repopulation of the territory. It was annexed to the University of Guglionesi, but in 1618 the Feudo di Petacciato was sold and taken over by the Duke of Celenza (Abruzzo) Giulio Cesare Caracciolo in 1619.
These contributed to strengthening that phase of repopulation and economic recovery of the country.
Towards the end of the 16th century Petacciato was invaded by the Turks, becoming a refuge for bandits.
In its long and troubled history, Petacciato also experienced the dominion of the D'Avalos, a noble Neapolitan family who contributed significantly to restoring economic, social, cultural and religious development to the town.
Petacciato, despite its thousand-year history, only became an independent municipality on 30 December 1923, breaking away from Guglionesi.