After studying applied cultural sciences in Hildesheim (majoring in music and art), Jörg Gollasch went to Berlin in 1997 to work at the Baracke am Deutschen Theater. There (and later at the Schaubühne) he worked as composer and musical director with Thomas Ostermeier on various productions, such as at the Baracke for Knife in Hennen, Shopping and Fucking, Disco Pigs as well as, among others, for Gier and Personenkreis 3. 1 at the Schaubühne am Lehniner Platz.
Since 2002 he has worked as a freelance composer, arranger and producer at various theaters in Germany and abroad (including Burgtheater Wien, Schauspielhaus Zürich, Schauspielhaus Hamburg, Berliner Ensemble, Deutsches Theater Berlin, Kammerspiele München, Residenztheater München, Schauspielhaus Bochum, Schauspiel Köln, Kretakör Theater Budapest, Maxim Gorki Theater) and with directors such as Claus Peymann, Karin Henkel, Dieter Giesing, Matthias Hartman, Tom Kühnel, Árpád Schilling, Thomas Langhoff, Haken Savas Mican, Oliver Reese and Robert Schuster. From 2013 to 2017, he also served as composer for Dieter Wedel’s productions at the Wormser and Bad Hersfelder Festspiele.
He has enjoyed a particularly close collaboration with director and artistic director Karin Beier since 2004. Their joint work has resulted in productions including The Work – On the Bus – A Fall (Elfriede Jelinek), The Dirty, the Ugly and the Mean (based on a film by Ettore Scola), both at Schauspiel Köln, and The Furious (with the participation of Ensemble Resonanz) at the Hamburger Schauspielhaus. 
For several years, Gollasch has also worked as a composer for radio plays and participated in productions for broadcasters such as SWR, SWF, RBB and Deutschlandradio. He is also active as a lecturer at workshops and as a teacher at the Ernst Busch Academy of Dramatic Art. In addition, he works as a film composer, including with directors Hank Levine, Hanno Olderdissen and Charly Hübner (Wildes Herz, 2017).