From approximately 3000 B.C., various carved monuments prove that there was life on the island. Those monuments were found in the are surrounding Kastri Theologos and on the Macedonian coastline across from the island.

The first references to Thassos appeared in Greek mythology. According to legend, while Thasus, son of the Phoenician king, Agenora, was searching for his sister, Europe (who had been abducted by Zeus, who had transformed himself into a bull) came and settled on the island. That is how Thassos got its name and has kept it from ancient times until today, although it has also gone by the names Hrisi, Heriei, Edonis, Odonis, Aithria and Demetra's Coast. According to Herodotus, it is known that the Phoenicians came to Thassos and took advantage of its natural metal and wood reserves (particularly in the area of Koinira from 1600 to 1500 B.C.).

Around the 7th century B.C., due to a prophecy from the Oracle of Delphi, The Parious came and settled on the island led by Telesikli and his son, Arhilogos, who was a famous poet in ancient times. From that time on, a strong Thassian state was created; a state that established colonies on the shores of Macedonia, fortified the capital of Thassos and established a strong, naval presence. Athens and Sparta wanted to gain control of the island. With ongoing wars, they both achieved this at various times throughout history. They did this because they knew that whoever controlled Thassos, had lots to gain, not only from the island itself, but also from its colonies on the mainland.

During this time, (5th century B.C.), Thassos' civilization flourished and many elements of it have survived to today. For example, sculpting, architecture and drama. In sport, Thassos was home to the undefeatable wrestler, Theogenis, Olympic winner. At that time, Thassos had a population of 150,000, fortified walls all around the island as well as a fortified port in the capital, a Senate, Deans' Offices, a marketplace, theatre, conservatory, etc.

Thassos' decline started around the time of the Persian Wars (492 B.C.) and in 340 B.C. came under the rule of King Phillip II of Macedonia. Then, it fell into the hands of the Romans during their reign until 330 A.D. After that, it was part of the Byzantine Empire. Piracy was a terrible problem for the island at that time. From the 7th century on, the problem worsened and the inhabitants began to create new villages in the outlying regions.

In 1353 A.D., Francisco Gatilouzi, from Genoa, conquered the island and his descendants maintained control until 1455 when Thassos was taken over by the Turks. In 1813, the Sultan passed control of the island to Mehmet Ali, Vizier of Egypt. Ali, who later found the Egyptian dynasty, was born in Kavala and grew up next to the family of Thodoros Karapanayiotis in Rahoni, Thassos. Due to his gratitude towards this family, Mehmet Ali exempted the island from paying any taxes. Despite this, the people of Thassos revolted in 1821 with their chieftan, Hatziyioryi from Theologo. Unfortunately, they were unsuccessful.

In 1902, new taxes were imposed on the island causing upheaval and the eventual relinquishing of Egyptian rule to be replaced by Turkish rule until 1912. Since then, Thassos has been free of foreign rule.