The Ruhr Museum's photographic collection sees itself as the pictorial memory of the Ruhr area. It exists since 1989, has been presented in exhibitions ever since and is constantly being expanded. It is now the largest and most important archive of historical and contemporary photographs of the region, its landscapes and cities, people, work and leisure, everyday life and festivities. The holdings of around 4 million negatives and several tens of thousands of prints and slides include extensive photographers' estates and archives such as those of Ruth Hallensleben, Willy van Heekern, Josef Stoffels, Anton Tripp, Marga Kingler and Peter Kleu. Also represented are important photographers from Ludwig Windstosser and Albert Renger-Patzsch to Bernd and Hilla Becher, Timm Rautert, Michael Wolf, Brigitte Kraemer, Manfred Vollmer and Joachim Schumacher. The period documented in the photographs ranges from the beginning of photography in the 19th century to the present day, with a focus on the fifties to the seventies of the 20th century.

The collection is open to all interested parties; it is used by scholars as well as by the media, other cultural and educational institutions and citizens who wish to inform themselves about certain aspects of the region's history and present. Since 2009, the main holdings of the photo archive have been accessible on the internet. Interested parties can conduct their own research in an online image database, view images and place orders.