In 5th-4th century BCE the territory of Giugliano was settled by the Osci, who founded, among the many cities, Atella and Liternum, both of them flourished under the dominion of Rome.

The city remained a small center until 1207, when Cuma was destroyed by the Neapolitans; some of the citizens from that town, including the clergy and the cathedral capitular, took shelter in Giugliano.

In 1495 Charles VIII of France, having occupied the Kingdom of Naples, gave the feud to Count Michele Riccio, from whom it was taken away with the defeat of the French.

In this period there was a notable boost to the economy and to the cultural and social growth of the Giugliano university, leaving various artistic testimonies.

[10] In 1647, Henry I, Duke of Guise descended into Italy with his army, with claims to the crown of Naples, and set up his camp in Giugliano with about 5,000 soldiers.

[11] During the seventeenth century the Mancini family was invested, probably for a short time, with the barony of Giugliano with Domenico Nicola II, former Marquis of Fusignano and Vice Grand Chancellor of the Kingdom of Naples.

It is located in a fertile coastal plain north-west of Naples, the so-called Agro giuglianese, thus serving as a market for agricultural products to the city.

The city is home to the studios of the television broadcaster Tele Club Italia, active in documenting news, sports and politics in the northern area of Naples.

[18] The city of Giugliano is mentioned several times in the episodes of the Gomorrah series,[19] when the Savastano Clan decides to intervene in the municipal elections.