In 1994 he went to Berlin working as a production manager on a number of German feature films with directors Wolfgang Becker, Max Färberböck, Nico Hofmann and Rainer Matsutani before he moved on to line-produce mostly international feature films in China, Israel, US, Canada, Russia and France.
After executive-producing the films Nightsongs (Competition Berlinale) and Hamburger Lektionen by Romuald Karmakar he co-produced the Bollywood action-blockbuster Don 2 with Excel Entertainment, Mumbai, directed by Farhan Akhtar featuring Shah Rukh Khan.
In 2013 and 2014, Mathias was line producing the Berlin shoot of Dreamworks' biopic The 5th Estate on Wikileaks founder Julian Assange directed by Bill Condon and Marjane Satrapi's Mandalay Vision production The Voices.
In Israel he produced Sharon Rhyba Khan's documentary Recognition and Erez Pery's The Interrogation followed 2016 by Ofir Graizer's The Cakemaker.
In 2021 Mathias has been line-producing the SKY UK Series Then You Run and service-producing the Berlin shoot of the Killing Eve season 4 and has produced the Netflix documentary ELDORADO for the Thursday.Company.