Born in Vienna in 1956, Thomas Riebl studied with Siegfried Führlinger, Peter Schidlof (Amadeus Quartet) and Sandor Végh. He won third prize at the International Competition in Munich /ARD 1976 and in 1982 first prize as well las the Ernst Wallfisch Memorial Award at the International Naumburg Competition in New York. Thomas Riebl has been invited to many of the major international music festivals (e.g. Salzburger Festspiele) and has appeared at venues such as Carnegie Hall, Concertgebouw Amsterdam and the "Goldene Saal" of the Wiener Musikverein. He has performed with numerous leading orchestras including the Chicago, Berlin and Vienna Symphony, the Bavarian, Finish and Vienna Radio Symphony Orchestras, with conductors such as Claudio Abbado, Horst Stein, Edo de Waart, Andrew Davies and Sylvain Cambreling.

His chamber music partners have included Jessey Norman, Andras Schiff, Oleg Maisenberg, Elisabeth Leonskaja, Pierre-Laurent Aimard, Gidon Kremer, Isabelle Faust, Joshua Bell, Tabea Zimmermann, Natalia Gutman, Sabine Meyer and leading string quartets. From 1972 - 1979 he was a member of the Franz-Schubert-Quartett, Vienna (first prize at the competition of the European broadcast cooporations in Stockholm in 1974); subsequently he became a founder member of the Vienna String Sextet (1979 - 2004), which performed worldwide and recorded several CDs for EMI and pan classics.
Since 1983, Thomas Riebl has been a professor at the Mozarteum University Salzburg. He has given numerous master classes worldwide, visiting the most prestigious universities, such as Guildhall/ London, UdK und Hanns Eisler/Berlin, Juilliard/N.Y., NEC/Boston and Curtis Institute/Philadelphia .
Many of his students won international competitions (Tokyo, ARD Munich) and became professors at music universities or members of leading orchestras and string quartets. He has been member/head of the jury at several international competitions, including ARD/Munich and Tokyo.

He is artistic director of the Internationale Sommerakademie Bad Leonfelden, Austria since 2003 and has recorded for RCA, pan classics and Hyperion Records. Several pieces have been written for him, e.g. the solo sonata by Gottfried v.Einem, the concerto by Ivan Eröd and the „Toccata for Thomas“ by Garth Knox. He gave the Austrian first performance of the concerto by A.Schnittke in Graz. Thomas Riebl is publisher of several arrangements for the viola, such as the sonata op.78 by J.Brahms (Edition Peters) and pieces and sonatas by R.Schumann, E.Grieg and J.Brahms (Partitura Verlag) In 2010 he developed, together with luthier Bernd Hiller, a five string tenor viola (with a low F string, made by Thomastik-Infeld) on which he performes F.Schubert ́s Arpeggione Sonata (low string tuned to E), J.S.Bach ́s lute version of his 5th cello suite (G – c – g – d – g1) and his 6th cello suite, his sonatas for viola da gamba, Beethoven ́s first cello sonatas op.5, Mozart ́s clarinet concerto (the original basset clarinet version), as well as recently written pieces for this instrument, including the “Toccata for Thomas” by Garth Knox.