Sankt Georg was founded in 1882 by Austrian Lazarists and was originally intended for German-speaking Catholic children living in the Ottoman Empire. After the Ottoman (and Austrian) defeat in World War I, the school was ordered closed by the occupying Triple Entente forces in Istanbul, and all of its staff was sent back to Austria. The school was reopened shortly afterwards when the Republic of Turkey was founded (1923). After the annexation of Austria by the Nazi Germany in 1938, the school turned into a "German school" and it was closed once again in 1944, due to the freezing of relations between Turkey and Germany. It was reopened in 1947. In 1995, the girls' and boys' schools were merged.