Skiathos history is deeply rooted within the centuries and its origins go back in the prehistoric era. The beauty of the environment, the safe and wide port which is secured by four small islands, its fertile land, and its marine wealth made it a pole of attraction for the races that were emigrating during the prehistoric era.

During the Persian wars, Skiathos port was used, due to the island's nodal point, as the base of the ancient Hellenic Triiris (triremes), with which the Persians' moves from the North were controlled.
It is said that the island's name derives from Mount Athos shade (“Skia” is the Greek word for “shade”) that falls over it.
Another version relates the derivation of the island's name with the small town Skia that is located in Evia Island, the town from which Halkideis (the residents of Evia) set out with the purpose to settle on the island.
The third and most dominant version about the island's name is that it derives from the thick shade the many trees of the island provide.

Pelasgi, who came from Thrace, are considered to be the first inhabitants of the island. In the 8th or 7th century B.C., Halkideis arrived, who founded a colony on the island's south side, where the concurrent city of Skiathos is located. In the year 480 B.C. the Hellenic Triiris that docked in Skiathos were completely discomfited by 10 triiris of King Xerxes' fleet. The king of Persia constructed and placed in Mirmix shallow shoal, located in Diavlos (channel) of Skiathos, a nautical sign which is considered to be the most ancient one known in naval history, in order for the Persian fleet to be prevented from a possible shipwreck. The blocks that constituted this nautical steel are kept today within the courtyard of the Hellenic Naval Academy. In the year 478 B.C., Skiathos became a member of the Athenian alliance. In this way, it got its autonomy and independency, but on the other hand, it was obliged to contribute to the alliance fund a tax for the service and maintenance of the alliance's fleet. When the Peloponnesian war ended (431-404 B.C.), and due to the fact that the Spartans dominated the Hellenic seas, Skiathos succumbed to Spartans from 378 to 377 B.C., when it was set free by the Athenian general Havrios and afterwards joined the Second Athenian alliance for the next 40 years (approximately). In 338 B.C., Skiathos was occupied by Filippos the second, King of Macedonia, who devastated the island. Democracy finally dominated when Filippos the second was defeated in Kinos Kefales by the Romans in 197 B.C. In 146 B.C. Skiathos succumbed to the Romans and helped them to their military actions. In 42 B.C. the Roman emperor Marcus Antonius gave Skiathos as a present to the Athenians, to whom it continued to belong during the reign of the Emperor Adrianos. Not many information is known about Skiathos during the early Byzantine period. The only thing that is known is that during the 3rd century the island's residents started to adopt Christianism. In the year 530 B.C. Skiathos became the base of the homonym bishopric, which belonged to the Metropolitan church of Larisa. After the conquest of Constantinople by the Crusaders and the dissolution of the Byzantine Empire, Skiathos, in 1207, was ruled by the Venetian family of Gizi. In 1276, the island, together with the rest of the Sporades island, came to the possession of the Byzantine Empire. During these years, the Turks and pirates often invaded the island; because of that the residents were forced to move to Kastro, a safer area on the north part of the island. Until 1390 Skiathos was the Apple of Discord between the Byzantines and the Enetians. In 1390 a Greek commander was appointed to rule the island, until 1453. With the fall of Constantinople to the Ottomans, in 1453, Skiathos residents requested the Enetians to occupy the island, so as to avoid the Turks, provided they would preserve the privileges that had attained during the rule of the Gizi family. The Turkish reign in Skiathos commences in 1538, when Harientin Barbarossa finally occupied it after six days of besiege. The island experienced many pirate raids during the Ottoman rule, and the decay was becoming more and more obvious. In the beginning of the 18th century, the shipbuilding and the shipping industry in general begins to flourish. Skiathos managed to organize a small fleet, with which it participated actively in the liberation struggle against the Turks. More specifically, the island participated in the battle of Tsesme with Admiral Orloff, in many raids that took place in the Turkish coastal areas with Lambros Katsonis as well as in the fights the chieftains of mountain Olympus carried out. In 1794 the monastery of Evangelismos tis Theotokou (Annunciation of Virgin Mary) was founded, which played a great role in the 1821 revolution, like all monasteries of the island that weren't destructed. They offered shelter to many rebellions. Skiathos residents offered, mainly, important naval services during the 1821 revolution. Ever since the London protocol of 1829 was signed, the island's capital was transferred from Kastro that was located on the north part of the island to the port where in the ancient years the ancient city of Skiathos was built. Kapodistrias founded the “Greek School” in the island as well as the “Interteaching School”, while in 1835 a school premise was constructed thanks to the residents who paid for it. Thus, slowly but steadily the city started to develop until it reached its current form. Skiathos shipping industry flourished at the end of the 19th century, an era during which many shipyards were founded, where remarkable shipbuilders, used the raw material the forests offered and constructed fast boats that ploughed the waves. Skiathos fleet dominated the Mediterranean in 1877 with 110 sailing ships. When the first steaming ships appeared, the gradual decay of the shipyards began. During the Second World War, the city of Skiathos was set to fire by the Germans and suffered a lot one more time.