Gustav von Myrdacz was born in Vienna, Austro-Hungarian Empire, on 12 July 1874 in a German-speaking Silesian aristocratic family. His father, Paul von Myrdacz (4 May 1847 – 7 July 1930), who was born in Konská (Třinec), pursued a career as a military doctor in the Austro-Hungarian Army. He was involved in the occupation of Bosnia in 1878 and spent time there in the 1880s.