Beginning in 1961, he started using photographic films, radiograms, and block prints, and further studied graphics at the Kunstakademie Düsseldorf, where he worked until 1963 with Coester.
After a year's residence in Paris at the studio of Stanley William Hayter, he returned to Berlin, and dedicated himself to various types of graphic design.
With his work since the mid-60s Brehmer was, along with Konrad Lueg, Sigmar Polke, Gerhard Richter and Wolf Vostell, an important representative of the capitalist realism style.
The best-known work of this group is a rigged German Flag (Korrektur der Nationalfarben, 1972), wherein the three colours black – red – gold valued in different sizes are defined by the distribution of wealth in West Germany.
Besides the graphics, panel paintings and drawings Brehmer produced films (such as "walking" 16 mm, 20 min., B / w, sound, Kleistfilm, 16 mm, 9 min., Color, sound, several documentaries on performances by J. Beuys, Moorman C., A. Kaprow, A. Koepcke, P. Polke and others) and compositions based on graphical templates (Seele und Gefühl eines Arbeiters, 1978; Composition No.
[citation needed] „KP Brehmer hatte es gar nicht so sehr auf Einzelausstellungen angelegt.