After leaving Hurtwood in 1998, German Hannah began her acting career as Mimi in the TV series Aus heiterem Himmel where she stayed for two years.
She took over the Tele 5-Clip-Show musicbox with her sister Sara at the end of 2002. She also started studying Communication Sciences in Vienna. She has had many television roles, including Jule in Das Böse Mädchen and since 2003 Vera in the series 18-Allein unter Mädchen. In 2003 she also had a part in Unter Verdacht: Beste Freunde and a smaller role in the sketch-comedy Tramitz & Friends.
Her roles became more ambitious with the television film Emilia - Die zweite Chance, where she played a patient with Borderline personality. In 2005 she received her first leading role as the murderer Jenny in Vier Minuten by Chris Kraus. January 19th 2007, she received the Bayerischen Filmpreis for best new female talent. In 2005 she played a suicidal youth in Das wahre Leben by Alain Gsponer. She ended her studies in Vienna and moved to Berlin in order to participate in these two films. For Das wahre Leben she was awarded the 2007 Deutschen Filmpreis for best supporting role and the Adolf-Grimme-Preis in 2009.
In 2007 Herzsprung played the terrorist Susanne Albrecht in the screen adaptation of the book Der Baader Meinhof Komplex as well as the leading role of Daniela in the film 10 Sekunden. In 2008 she played the role of Julia in Stephan Daldrys' film Der Vorleser. She also played the role of Charlotte in Uwe Jansons' adaptation of Goethe's Die Leiden des jungen Werther, as well as in Jo Baiers' television movie Liesl Karlstadt und Karl Valentin as young Liesl Karlstadt.