The first prize winner of several competitions with the instruments of clarinet, piano and cello, Ottensamer has performed as soloist and chamber musician worldwide with partners such as the Vienna Virtuosi (members of the Vienna Philharmonic), the Vienna Chamber Orchestra and performers including Leif Ove Andsnes, Angelika Kirchschlager, Julian Rachlin and Yo-Yo Ma. In 2005, together with father Ernst Ottensamer and his older brother Daniel Ottensamer (both solo clarinettists of the Vienna Philharmonic), formed the clarinet trio The Clarinotts. The ensemble gives concert tours in Austria, Germany, Italy, Japan, the United States, performs at festivals all over the world, appeared on TV and radio and in 1999 recorded a CD published by Gramola Vienna and Octavia Records.
In 2013 Ottensamer entered an exclusive recording agreement with Universal Classics's Mercury Classics label, in partnership with Deutsche Grammophon. This makes him the first clarinetist to release exclusively through DG. His debut album, Portraits - The Clarinet Album, was released in June 2013 internationally through Mercury Classics]/Deutsche Grammophon and features concertos by Domenico Cimarosa, George Gershwin and Aaron Copland recorded with the Rotterdam Philharmonic Orchestra and Yannick Nézet-Séguin.