The area around Giurgiu was densily populated in the time of the Dacians as archeological evidence shows and even the capital of Burebista was in this area (it is thought to be in Popesti on the Arges river). During the Roman times this was the site of Theodorapolis, a city built by the Roman emperor Justinian (483-565).
The city of Giurgiu was probably established in the 14th century as a port on the Danube by the Genoese merchant adventurers, who established a bank, and a trade in silks and velvets. They called the town, after the patron saint of Genoa, San Giorgio (St George); and hence comes its present name. It was first mentioned in Codex Latinus Parisinus, in 1395 during the Mircea cel Batran and was conquered by the Ottomans in 1420 as a way to control the Danube trafic.
As a fortified town, Giurgevo figured often in the wars for the conquest of the lower Danube; especially in the struggle of Mihai Viteazul (1593-1601) against the Turks, and in the later Russo-Turkish Wars. It was burned in 1659. In 1829, its fortifications were finally razed, the only defence left being a castle on the island of Slobozia, united to the shore by a bridge.