Symeon was from Trapezoun. He succeeded Mark II in the middle of 1466 and remained onto the Ecumenical throne a few months until the end of 1466.
After the first patriarchy of Dionysios I, he was re-elected (end 1471), but after 3 years he was forced to resignation following wrong accusations. He then resorted to some monastery close to Stenimachos, where he stayed seven years. In April 1482 he was called again to the Patriarchical throne.
During his last patriarchy, he summoned a council which condemned the uniat council of Florence and composed a Service for those who renounced Roman Catholicism and wished to become Orthodox.
Towards the end of 1486, he was succeeded by Nifon II.