Demetrius was born in Constantinople to Zannis Stefanovich Schilizzi (1806–1888), one of the Schilizzi merchant and shipping family originally from Chios, and Eleni Vouro. The Schilizzi family was one of the trading dynasties that arose after the 1822 Chios massacre of the Greek War of Independence. Demetrius' uncle J. S. Schilizzi (1805–1892) was in the Black Sea grain trade at Livorno, and founded a London branch in 1837. Demetrius Schilizzi began his banking career in Paris.