Born in Berlin, Sredzki was a lathe operator and in 1918, he joined the Independent Social Democratic Party of Germany (USPD).
He worked in leading positions in leftwing organizations, such as member of the Reich leadership of the League of Proletarian Freethinkers and leader of the Federation of the Friends of the Soviet Union, Berlin District.
After Adolf Hitler and the Nazis seized power in Germany, Sredzki was active in the resistance struggle.
On 7 December 1934, he was arrested by the Gestapo, and on 9 June 1936, he was sentenced by the Berlin Superior Court (Kammergericht) to five years in labour prison (Zuchthaus).
The stele "Traditions of the German Working Class" by Heinz Worner (Knaackstraße 53–67 in Prenlauer Berg, on the same street as the aforesaid school) is dedicated to the murdered antifascists Ernst Knaack and Siegmund Sredzki.