Strategically set near the confluence of the Bosphorus and the Black Sea, the future site of Yoros Castle was settled by the Phoenicians and Greeks prior to the Byzantine period for trading and military purposes. The Greeks called the area Hieron (Sacred Place). The remains of temples, including Dios, Altar of the Twelve Gods, and Zeus Ourios (Zeus, granter of fair winds) were discovered in the area, dating to centuries BCE.
Yoros Castle was intermittently occupied throughout the course of the Byzantine Empire. Under the Palaiologos dynasty during the decline of the empire, Yoros Castle was well fortified, as was the Rumeli Kavağı on the opposite side of the Bosphorus. A massive chain could be extended across the Bosphorus between these two points, cutting off the straits to attacking warships, similar to the chain across the Golden Horn which was used to defend Constantinople during the last Ottoman siege by Sultan Mehmed II.
Byzantines, Genoese, and Ottomans fought over this strategic fortification for years. It was first conquered by Ottoman forces in 1305, but retaken by the Byzantines shortly thereafter. Bayezid I took the castle again in 1391 while preparing for his siege of Constantinople. It was used as his field headquarters during the construction of Anadoluhisarı, one of the more important castles for the siege. In 1399 the Byzantines attempted to take back Yoros Castle. The attack failed, but the village of Anadolu Kavağı was burned to the ground. The Ottomans held the fortress from 1391–1414, losing it to the Genoese in 1414. The forty-year Genoese occupation lent the castle its moniker of Genoese Castle.
Upon Sultan Mehmed II’s conquest of Constantinople in 1453, the presence of the Genoese at such a strategic location posed a threat to the new Ottoman capital. Within a few years, Sultan Mehmed drove the Genoese out. He then fortified the walls, and constructed a customs office, quarantine, and check point, as well as placing a garrison of troops there. Bayezid II (1481–1512) later added a mosque within the castle walls.
Cossack raids had plagued the Ottoman Empire throughout its long history. In 1624 a fleet of 150 Cossack caiques sailed across the Black Sea to attack towns and villages near Istanbul. They struck villages inside the Bosphorus, and Murad IV (1623–1640) refortified Anadolu Kavağı to defend against the fleet. It would prove instrumental in securing the region from seaborne Cossack raids.
Under Osman III (1754–1757), Yoros Castle was once again refortified. Later, in 1783 Abdülhamid I added more watchtowers. After this period, it gradually fell into disrepair. By the time of the Turkish Republic, the castle was no longer used.