As a young man, he worked as a fine artist, illustrator, and bookbinder in his native Hamburg. In 1899, Behrens became the second member of the recently created Darmstadt Artists' Colony, where he designed and built his own house as well as everything inside it—from furniture and textiles to paintings and pottery. While at Darmstadt, he realized that he was more interested in simplified geometric forms than the more organic and curvilinear forms of the current Jugendstil (New Art) or art nouveau. In the early 1900s, he became one of the leaders of architectural reform in Germany and one of the first architects of factories and office buildings utilizing a modernist materials palette of brick, steel, and glass.
As a teacher, his ideas and teachings on design for industry, as well as everyday objects and products, influenced a group of students that would ultimately alter the direction of twentieth-century architecture and design worldwide, including Ludwig Mies van der Rohe, Le Corbusier, Adolf Meyer, and Walter Gropius, founder of the Bauhaus school in Dessau, Germany.
In 1907, Allegemein Elektricitäts-Gesellschaft (AEG), Germany's largest electrical utility and industrial producer, hired Behrens as their new artistic consultant. It was at aeg that he created a unified brand for every aspect of the company's visual environment—office buildings, factories, and visual communication materials.
A primary example of Behrens's design philosophy at aeg was a promotional poster he designed advertising AEG's newest product in 1910—a technologically advanced lamp or lightbulb. The design of the poster is clearly based on fundamental modernist design elements and principles. Its orthogonal graphic composition is organized with an articulated grid and comprises basic geometric shapes—a continuous frame or square, a circle, and an equilateral triangle. The triangle provides a focal location for the lightbulb and a simplified, abstract dot pattern represents brilliance and illumination. The pattern and lines framing and dividing the composition of the poster, as well as the outline of the circle and triangle, are all composed of a series of dots or points, which symbolize and communicate light.
In defining his approach, Behrens stated, "Design is not about decorating functional forms—it is about creating forms that accord with the character of the object and that show new technologies to advantage."
His visionary approach not only influenced the entire aeg corporate culture, it became the first seminal example of corporate identity and branding that would inevitably become a primary force within the design professions in the later part of the twentieth century.