Lyssaridis was born in the town of Lefkara, Larnaca province, on May 13, 1920. He studied medicine at the University of Athens and returned to Cyprus a medical doctor. When the EOKA struggle broke out on April 1, 1955, he was one of a few leftists who joined up.
In 1960, when Cyprus achieved independence, Lyssaridis was elected to the House of Representatives under the banner of the Patriotic Front. Late in 1963, when intercommunal strife broke out on the island, he headed a band of Greek-Cypriot volunteers who fought at Omorfita, the Pentadaktylos mountains and Kokkina.
In 1969, Lyssaridis founded EDEK, a moderate socialist party, as an alternative to Cyprus' conservative parties and the communist AKEL. EDEK party members fought against the right-wing elements that staged a coup d'etat on July 15, 1974 against President Makarios. Soon afterwards, Turkey invaded the island. On August 30, of that same year, an attempt was made on Lyssaridis' life. Lyssaridis himself, though injured, escaped with his life however EDEK youth movement president, Doros Loizou, was killed in the attempt.
Lyssaridis continued to serve in the House of Representatives. He served as its President between the years of 1985 and 1991. In 2000, he founded KISOS which incorporated EDEK and others of similar political persuasion. In 2006, he ended his long Parliamentary career, claiming that he is only retiring from Parliament and not from politics.