Since 1997, Silke Zimmer has been working as a trade union secretary with various functions for trade union trade, banks and insurance, at a later time ver.di Vereinte Dienstleistungsgewerkschaft e.V. In 1999, she transferred to the regional department for trade, banks and insurance. Since 2012, Silke Zimmer has been the head of the regional department for trade (ver.di North-Rhine Westphalia) and serves as negotiator in trade related employment matters as a representative of the union in North-Rhine Westphalia. Since 2017, Silke Zimmer has been a member of the supervisory board of METRO AG.