The Karl Ernst Osthaus Museum in Hagen is a foundation that takes its name from the art historian and collector (1874-1921) who promoted modern architecture and design and converted his birthplace of Hagen into an artist's colony, a space to debate modern German design. The Hagen initiative responded to the aim of renewing people's lives via their incorporation into a context dominated by art and culture.

As part of this project, Osthaus founded the Folkwang Museum in Hagen, in a Renaissance style building and with the initial aim of gathering together a natural sciences collection. In 1900, he commissioned Henry Van de Velde to remodel its rooms so that it could also house an art collection. He also opened the German Museum for Art in Commerce and Industry to promote quality design in industrial objects.

But the collections were dispersed when he died in 1921. The museum was again opened in 1945, with the name that it currently has, as a tribute to its creator. The museum was also renovated in 1992 and its Art Nouveau interiors were restored.