From 1999 Müller completed a post-graduate course at the Academy of Media Arts Cologne under Michael Lentz and Wolfgang Becker.

Müller's second feature film Wallace Line (Die Liebe der Kinder) (2009) was released in German cinemas in 2010.

It tells the story of an former couple whose attempt to shoot a comedy about the European Football Championship in Poland threatens to descend into chaos.

[2] In addition to his work as a director, screenwriter and producer, Müller has been involved in cinema programming at Filmclub 813 in Cologne since 1999.

At the movie theater Kino 813 in der BRÜCKE in Cologne, he brought out the first complete retrospective of all of John Cassavetes' directorial works.