Kampwirth graduated from
Franz Stock High School in
Arnsberg in 1986 and then did his civilian service as an ambulance driver in
Munich. After training at the Hamburg drama studio from 1989 until 1992 under the direction of Hildburg Frese, Kampwirth worked at the
Schiller Theater in Berlin, the
Burgtheater in Vienna, and the
Kammerspiele in Munich. He performed under the direction of
Leander Haußmann,
Dieter Dorn,
Georg Ringsgwandl, and
Helmut Griem. His film and television career began in the early 1990s with smaller roles in television series such as
Großstadtrevier,
Wolffs Revier, and
Tatort. He became known to a wider audience with the television miniseries
Ein unmöglicher Mann and the film version of
Amelie Fried's novel
Der Mann von Nebenan, in which he played the role of Lukas Lander. Kampwirth has been part of the
Hamburg Kammerspiele ensemble in his adopted home of Hamburg since 2007. From 2013 until 2015, he played Dr. Bode in the television series
Lerchenberg. In 2016, he played the role of Walter Richter in the film adaptation of
Peter Stamm's
Agnes, next to , who portrayed the titular role. Since 2017, Kampwirth has held one of the lead roles in the
Netflix science fiction series
Dark, that of Peter Doppler. ==Selected filmography==