The roots of Demag date back prior to its formation, but became Märkische Maschinenbau-Anstalt, Ludwig A.-G in 1906 as the biggest crane building company in Germany employing 250-300 people.

The Märkische Maschinenbau-Anstalt L. Stuckenholz AG traces back to the machine factory Mechanische Werkstätten Harkort & Co., founded 1819 in Wetter an der Ruhr, already beginning the manufacturing of cranes in 1840.

During the Second World War, armoured fighting vehicles (in particular Bergepanther) were built in the Berlin Staaken plant.

During the buildup to, and during World War II, Demag-designed halftrack military vehicles, both in unarmored "artillery tractor" models in the late 1930s, the basis for the powertrain of their armored Sd.Kfz.

Demag would soon expand into construction machines, vehicle cranes, moving and conveying engineering (workshop crane and control devices), steel mill technology (complete metallurgical plants, in particular continuous casting equipment), compressors, and compressed air engineering.

In 1983 Mannesmann-Demag AG and Wean United, Inc. of Pittsburgh, United States, founded a daughter company to produce steel working equipment, Mannesmann Demag Wean Co. A joint venture with the Japanese manufacturer Komatsu led to spinning off of the large-scale excavation operations and their renaming as Komatsu Mining.

The compressor division was sold in 1996 to CompAir, which was then part of the British Siebe/Invensys group, but has since become an independent company.

[6] KKR initiated a major reorganization of the Demag Crane & Components organization, including a refocused effort of their product lines.