Following his vocational training in business, Gerald Müller was employed at Robert Bosch GmbH from 2006 to 2009, where he worked in Strategic Procurement. This was followed by a one-year trainee program at the IG Metall trade union in Frankfurt/Main. From the end of 2010 he was then responsible for a joint project of the IG Metall branch offices in Reutlingen-Tübingen and Albstadt. Since 2014 Gerald Müller has held the position of trade union secretary for IG Metall Reutlingen-Tübingen. At the beginning of 2020 he was elected as the second authorized representative and treasurer of the branch office.