Ios has been inhabited since the Neolithic era and especially the Early Cycladic period (3rd millennium BC), as attested by the significant, award-winning settlement of Skarkos, one of the best-preserved in the Aegean. During the Minoan era the island received influences from Cretan and Cycladic culture, before the Ionians and Dorians settled here around 1100 BC.
In antiquity, the name of Ios was inextricably linked with Homer: according to tradition, his mother came from the island, and here he died and was buried, at the site of Plakoto. In the classical period Ios was a member of the Athenian League, and traces of ancient temples, an aqueduct and fortifications survive.
In medieval times the island was fortified at Paleokastro, and in 1397 the Venetian lord Marco Crispo reinforced the walls of Chora. In 1537 Ios passed to the Ottoman Empire; thanks to its safe harbor it was called "Little Malta". Ios actively took part in the Revolution of 1821, and Spyridon Valetas, the first Minister of Education of the newly-formed Greek state, came from Ios.
In modern times, from the 1960s-70s, Ios became a magnet for hippies and later a symbol of the Cyclades' youth nightlife. In recent decades it has steadily upgraded as a quality tourist destination, combining its liveliness with respect for its natural beauty and historical heritage.