Mathias Fehn studied English and Music at the TU Dortmund University for the teaching profession Sek II/I. He also completed additional studies in German as a Second Language / Intercultural Education at the University of Duisburg-Essen. He also completed additional studies in German as a Second Language / Intercultural Education at the University of Duisburg-Essen. He is a teacher at a grammar school in Cologne. As a facilitator for the district government of Cologne, Mathias Fehn has been active in the areas of German as a second language, language sensitivity, and heterogeneity / internal differentiation as well as in school development consulting since 2016.

Since 2020, Mathias Fehn has been a part-time deputy teacher at the Mercator Institute for Language Support and German as a Second Language in the area of language and profession. He is responsible for advising and accompanying elementary schools in language-sensitive school development as part of the support program Language Education in Multilingual Classes.