Born to Greek parents in Istanbul, and after a sojourn in Athens (1958–1962), he moved to Switzerland with his family in 1962, aged seven, and was later[year needed] naturalized as citizen of Lausanne.
During 1996–1998, he was a member of the cantonal government of Vaud (Conseil d'Etat), heading the department of Justice, Police and Military affairs.
At the October 2007 federal elections, Zisyadis failed to win reelection, however, on 1 November 2007 successful party candidate Marianne Huguenin announced her resignation from the National Council to focus on her position as mayor of Renens, leaving Zizyadis to take the Party's seat in the National Council representing Vaud.
Zisyadis again failed to retain his mandate in the 2011 elections, his seat passing to the Social Democrats.
The Alternative Left coalition gathered 1.2% of the popular vote nationwide; with the loss of Zisyadis' seat, the far-left loses all representation at the federal level.