According to mythology Nisyros is a creature of the God of the sea. The myth says that Poseidon during a battle with Polifotis cut part of Kos and threw it on the giant. This rock weight on the giant and created Nisyros. It is said that Polifotis is not dead but still lives in the bowels of the island. Wounded as he is, moans and an earthquake or a volcanic eruption occurs in the island. This is how mythology justifies the existence of volcano in Nisyros, as and the close relations with Kos.
Historic sources refer that the island was created due to volcanic eruptions. As first settlers are reported Kares. Rhodians and Thessales followed.
Nisyros became part of the Athenian Coalition in 479 BC.
From excavations in the archaeological site of acropolis it is shown that the island had an important civilization in ancient times. The ancient town was inside the acropolis walls and was inhabited from the 5^th BC to the 5^thAC.
Close to the port are found the remains of an ancient town from copper Age.
Nisyros during history followed the rest of Dodecanese islands. In 1315 was conquered by the Knights of Saint John, who built the Venetian castle.
In 1522 Turkish domain the island until 1912, when Italians conquer it.
As all Dodecanese islands, Nisyros was adjusted to Greece in 1948.