Coburn opened a studio in New York City and became a member of the Camera Club. In 1903 Coburn joined with Alfred Stieglitz, Edward Steichen, Clarence White and Gertrude Kasebier to form the Photosecession Group.
In 1904 Coburn moved to London where he developed a reputation for photographing the portraits of celebrities such as George Bernard Shaw and George Meredith. Coburn's portraits were collected and published in the books, Men of Mark (1913) and More Men of Mark (1922).
In London Coburn associated with a group of artists who called themselves Vorticists. The group included Wyndham Lewis, Henri Gaudier-Brzeska, Charles Nevinson, and William Roberts. In his journal, Blast (1914-15), Lewis attacked the sentimentality of 19th century art and emphasized the value of violence, energy and the machine. In the visual arts Vorticism was expressed in abstract compositions of bold lines, sharp angles and planes. At this time Coburn began experimenting with what he called vortographs. These were abstract pictures of crystals taken through a triangular tunnel of mirrors called a Vortoscope.
In the 1920s Coburn became increasingly interested in mysticism. However, he continued to take photographs until his death in Denbighshire, Wales, on 23rd November, 1966.