Anna Sophia Blersch trained as a dressmaker after leaving school. She then studied stage and costume design at the Mozarteum in Salzburg. After graduating, she worked as a costume assistant to Moidele Bickel at the Salzburg Festival and as a permanent assistant costume designer at the Deutsches Nationaltheater Weimar. From 2000-2002 she was a permanent stage and costume designer at the Heidelberg Theatre.
Since 2002 she has worked as a freelance stage and costume designer at numerous theatres such as Staatstheater Darmstadt, Theater Erlangen, Staatstheater Schwerin, Theater Bielefeld, Rheinisches Landestheater Neuss, Theater Lübeck, Landestheater Eisenach, Theater Koblenz, Theater Rudolstadt, Volksbühne Frankfurt, Theater Regensburg, Staatstheater Meiningen, Badisches Staatstheater Karlsruhe, Pfalztheater Kaiserslautern, Theater Chemnitz, Festival Barock am Main.
Parallel to her theatre work, Anna Sophia Blersch runs a studio shop under the label fia-costumes in Weimar, where she lives with her family.