The party was founded by Vassos Lyssarides in 1969 as the United Democratic Centre Union, EDEK (Greek: Ενιαία Δημοκρατική Ένωση Κέντρου, romanized: Eniaia demokratiki enosi kentrou, ΕΔΕΚ).

EDEK, and Lyssarides personally, enjoyed very good relations with Third World socialist leaders and governments,[7] including Hafez al-Assad of Syria, Muammar Gaddafi of Libya[2] and Gamal Abdel Nasser of Egypt.

Members were drawn from the committee for re-establishment of democracy in Greece, and fighters from Lyssaridis's group during the 1964 clashes between Greek and Turkish Cypriots.

Several members of the party's youth section (EDEN) with Trotskyist tendencies were expelled between 1979 and 1984, who then formed Aristeri Pteryga (Left Wing).

EDEK was one of the most outspoken opponents of the Annan Plan for the reunification of Cyprus, which was voted on, and ultimately rejected by the Greek Cypriot community in the 2004 referendum.

EDEK backed Dimitris Christofias of the Progressive Party of Working People (AKEL) in the second round of the February 2008 presidential election.

[14] In February 2010 EDEK quit from the government coalition due to its dispute concerning the decisions of Dimitris Christofias in the Cyprus Problem.