Under the supervision of David Papineau he obtained a PhD in Philosophy in 1994 from King's College London with a thesis titled Science and Realism: A Naturalistic Investigation into Scientific Enquiry.

In the midst of the Greek socio-economic crisis he organised the 3rd congress of the European Philosophy of Science Association, in Athens, in October 2011.

In 2008 Psillos was elected member of l’Academie Internationale de Philosophie des Sciences (AIPS).

In March–May 2013, he delivered the Cardinal Mercier lectures in Philosophy at the Université catholique de Louvain, in Belgium.

In 2015, he was elected member of Academia Europaea (Academy of Europe)[16] for his contribution to promoting learning, education and research.