After a one and half year hitch in the German Army Jörgensmann worked with handicapped children and studied social pedagogics, but he never brought it to a conclusion.

During a career spanning three decades as a free improviser Jörgensmann has worked with (among many others) Mike Richmond, Barre Phillips, Kent Carter, John Lindberg, Charlie Mariano, Wilber Morris, Eric Vloeimans, Jeanne Lee, John Fischer, Vincent Chancey, Kenny Wheeler, Paul McCandless and Lee Konitz.

He was a member of Willem van Manen's Contraband (1985–1998), Andrea Centazzo's Mitteleuropa Orchestra (1983–1985), John Fischer's Interface (1981–1996) and Franz Koglmann's Pipetet (1983–1985).

In 1997 he started the Theo Jörgensmann Quartet, which toured in North America in 1999, 2001, and 2003, including playing twice at Montreal International Jazz Festival (1999 and 2003).

In 2009 Jörgensmann performed a few concerts with younger musicians from UK (Seb Rochford, Dominic Lash, Shabaka Hutchings and Noel Taylor) in London.

The members of the group are Perry Robinson, Gianluigi Trovesi, Bernd Konrad, Albrecht Maurer, Sebastian Gramss and Günther "Baby" Sommer.