Upon returning to Berlin at the age of 18, Koffler applied for admission to the Ernst Busch Theater School, but was rejected.

to study acting until 2007 at the Max Reinhardt Seminar in Vienna, where he would play roles in various theatrical productions directed by Klaus Maria Brandauer.

After several performances in television, theater, and cinema, in 2013 he starred in the film Free Fall, along with Max Riemelt and Katharina Schüttler.

In 2015, he was nominated for a Best Actor for the Deutscher Filmpreis for the drama/documentary film Tough Love (Härte), by director Rosa von Praunheim, in which he plays Andreas Marquardt.

In 2018, he starred in Florian Henckel von Donnersmarck's Oscar-nominated film Never Look Away with Tom Schilling, Sebastian Koch, Paula Beer, and Saskia Rosendahl.