The origins of Orbetello date to the Late Villanovan period (VIII century b.C.), the time during which the Etruscan civilization appeared in Tuscany. This coastal centre in the province of Grosseto with a population of 15,000 inhabitants keeps numerous traces of the ancient populations that inhabited it.

The Villannovan, for instance, a population that had already settled the area around the X century b.C., built the "Cyclopean Walls" of Orbetello. The numerous finds in the archaeological area of Cosa, near the chief town, are evidences of the ancient origins of the area. Inside the town, also the Dome with many doors rises with its Gothic-Tuscan façade and it recalls the medieval story of the town. The territory of Orbetello has always been very yearned for its geographical position which was ideal for the creation of a commercial call on the Tyrrhenian Sea. The excavations carried out in the town have unearthed the remains of buildings, probably warehouses that show the centre had been active in naval commerce since the VI century b.C.! In the centuries that precede the year 1000, Etruscans, Romans, Byzantines and Lombards ruled this area.
Any historical information on Orbetello of its first centuries after the fall of the empire does not exist, as it is the case for many other towns of the Italian peninsula. The first document where the town's name appeared dated to 805. It was a bull issued by Charles the Great and Pope Leo III by means of which the territories of Orbetello were given to the "Abbazia dele tre Fontane". Then, the Aldobrandeschi, of Lombard origins and the town of Orvieto became the rulers of the area and, finally, the Orsini of Pitigliano established their presence here at the half of the XIV century.
In the XV century, after Naples had dominated the town for a short period, Orbetello entered the Republic of Siena. After a little more than a century, yet, the Spanish arrived here. Philip II, the King of Spain, nominated it capital of the "Stato dei Presidi", two parts of the territory in the Tyrrhenian coast and of the Isle of Elba that enclose a portion of sea. Spain used this small state as a call and as a military garrison for those ships that put it into communication with the kingdom of Naples. It was in this period that the most important fortifications rose.
In 1707, Spain lost its territory in favour of the imperial troops. The Borboni of Naples conquered Orbetello in 1736 and the French revolutionary armies that Napoleon had sent in Tuscany, occupied it in 1801. Thus, the town became part of a Tuscan state again, namely the Kingdom of Etruria, which took back its name of Grand Duchy of Tuscany after the Restoration of 1815 and had the Hapsburg-Lorraine as rulers, again. In 1860, a Plebiscite annexed Orbetello to the Kingdom of Italy.