Born in Athens, Dionysopoulos studied Classical Philology, History and Archaeology at the University of Athens, Egyptology at the University of Cairo, Epigraphy, Papyrology and Numismatics at the University of Liège. He has worked as an archaeologist on excavations and as teacher and head teacher at secondary schools in Greece and abroad. He was a research associate of the Academy of Athens and Education Advisor for the Humanities. Passionate about the preservation of the natural environment and cultural heritage, he fought for the protection of Vouliagmeni Lake and succeeded in its recognition, along with its wider area, as a Natural Heritage Region and its inclusion in a Zone of Total Protection. He also contributed to the effort to prevent the construction of a rowing lake in the field of the battle of Marathon, participating as an expert in the application made to the Council of State by the Archaeological Society of Athens among others. He took also part in the International Conference on the Battle of Marathon which was held in Marathon in September 2008 under the aegis of the Ministry of Culture and the local municipality. His historical, archaeological, philosophical and pedagogical studies have been published in a variety of academic journals.