The Märkische Museum contains a collection of about 4000 pieces by 20th century German painters and graphic artists. Current developments in contemporary German and international art are also on display in rotating exhibitions.

The museum’s roots can be found in the "Verein für Ort- und Heimatkunde in der Grafschaft Mark zu Witten" (The association for local geography and history in the Mark zu Witten county) founded in 1886. The museum was built for the collection between 1909 and 1912 (reopened 1952) – its ground plan is based on a three-naved church. The museum was extended from 1985 to 1988 with an annex based on the principle of open-plan spaces. This was a modern way to continue the communicative structural of the collection presentation. The museum has been run by the city of Witten since 1944.

It provides an overview of developments in German art since 1900. The German Informel movement plays a central role in this collection which is one of the largest of its kind and contains some of the most important protagonists for example K.O. Götz, Hans Hartung, Gerhard Hoehme, Emil Schumacher, Fred Thieler and many others. The development of abstraction as it is manifested in Informel art is complemented here in various focus points such as the surreal tendencies of the post-war period. The new presentation of the collection shows the conditions and development of abstraction in Germany.

The collection began to be built up during the period of evaluation following expressionism. Ernst Ludwig Kirchner and Emil Nolde for example are among the important representatives of the Märkische Museum with Westphalian expressionists receiving particular attention. Westphalian artists have also been put in the spotlight with regard to new objectivity. Critical realism works from the 1960s and 1970s represent a continuation of this object-based development. Equally, the collection documents various trends in geometrical abstraction and their further development with works by Josef Albers, Leo Breuer, Adolf Luther or the Dusseldorf ZERO group.