In early October 1817, at the urging of the Countess Elding, wife of the Duke of Weimar and spokesperson of the Philomousos Eteria of Vienna, he went to Jena.
In 1824, upon the recommendation of the English colonel Leicester Stanhope, Psyllas undertook the publication of the Εφημερίς των Αθηνών ("Newspaper of Athens",[3] August 1824 – April 1826).
Later, Psyllas was appointed by Ioannis Kapodistrias as member of the Panellinion and first secretary of the Department of the Interior (January 1828) and three months later (April 1828) as Emergency Commissioner of Lower Messenia.
[4] Following the arrival of King Otto he was appointed by the Regency as commander of Euboea (March 1833) and a month later as Secretary of State (i.e., Minister) for Internal Affairs.
After the discovery of the conspiracy that led to the trial of Theodoros Kolokotronis, he was removed from the Council of Ministers (October 1833) and became prefect of Attica and Euboea and State Counsellor.
When the Council of State was established according to the provisions of the Greek Constitution of 1864, he agreed to take over the vice-presidency of this short-lived advisory body which was abolished in November 1865.