Katja Haß was born in 1968 in Krefeld. She completed her training in Stage and Costume design with Erich Wonder in Vienna. She then spent two years working as a stage design assistant to Anna Viebrock at Hamburg's Schauspielhaus. She was employed as a set designer at the Stuttgart State Theatre from 1996 to 2000. Since then, she has worked regularly with Stephan Kimmig, designing almost all the sets for his productions in recent years. From 2000 to 2002, Katja Haß was the studio manager and a stage designer at the Thalia Theater. She worked on Goethe's Stella at the Deutsches Theater in 2002, and on The Golden Fleece by Franz Grillparzer at Vienna's Burgtheater in 2004. Her designs for the Thalia Theater included the sets for: The Bus by Lukas Bärfuss; Penthesilea by Heinrich von Kleist; Buddenbrooks, based on Thomas Mann’s novel; Die Beißfrequenz der Kettenhunde (The Biting Frequency of Guard Dogs) by Andreas Marber; A Streetcar Named Desire by Tennessee Williams; Kasimir and Karoline by Ödön von Horváth; Dennis Kelly's Love and Money; and for A Flea in Her Ear by Georges Feydeau.
In September 2007, Katja Haß won the Karl Schneider Prize awarded by the City of Hamburg. And in 2008, together with director Stephan Kimmig, she was the recipient of the 3-sat Innovation Prize for “visionary contributions to German-language theatre”, for her stage design for Mary Stuart. Katja Haß was the Deutsches Theater's studio manager for the 2009/10 and 2010/2011 seasons.