Behrens started his career as a painter, illustrator and book-binder but would eventually become an artistic consultant for AEG (Allgemeine Elektrizitäts-Gesellschaft, literally General Electric Company). His career at AEG started in 1907 and there he designed a wide range of materials for the company including a logotype, product packaging and various publicity materials. The work he did there is of significant note because it is generally recognized as the first fully developed corporate identity, much preceding the corporate identity heydays of the 1950s and 60s. His work was not limited to printed materials, he also designed a turbine factory for AEG shortly after it entered the field of aircraft production.
AEG was eventually bought by the Daimler-Benz company in 1985.
Behrens turned to architecture after designing and building his own home. He even conceived the items in the interior, towels, shelves, furniture and everything in between. He was one of the pioneers of architectural reform, and his factory buildings designed of brick, glass and steel gained popularity during the early 20th century. During the years between 1907 and 1912 Behrens had many assistants and students including architecture big wigs Mies van der Rohe, Le Corbusier and Adolph Meyer.
Behrens list of students also included Walter Gropius who would later become the first director of the Bauhaus.