Was born in Norway. After graduating from his final exam in Hamar, he studied at the Norwegian Musical High-School in Oslo and at the Stockholm Opera-School. His vocal-teachers were Nicolai Gedda, Tito Gobbi and Sir Peter Pears among others.
He made his stage-debut as Ferrano in Mozart's Cosi fan tutte at the Royal Opera House Stockholm and remained closely related to this theatre for some seasons singing numerous lyric tenor-roles there. He joined the company of the theatre in Koblenz (Germany) in 1986 where he sang his first Rodolfo in Puccini's La Boheme, Stewa in Janacek's Jenufa and Boris in Katja Kabanova and he became a member of the Musiktheater im Revier Gelsenkirchen. In the early 1990-ies the artist also made his debuts with the Munich Gärtnerplatz-Theatre and the Wiesbaden State Theatre. Within the last years he sang many guest-production in various German opera-houses including roles like Don José in Bizet's "Carmen", Alfredo in Verdi's La Traviata, Alvaro in Verdi's La Forza del Destino and Pinkerton in Puccini's Madama Butterfly. Concerts and opera-productions made Tom Martinsen appear also in Schwitzerland, Austria and The USA. He also frequently participated in Summer Festivals in Vienna and Salzburg.
Within the season 1991-92 the artist made his debut with the Saxonian State Opera Dresden (Semperoper) singing the title-role in Jacques Offenbach's Les Contes d'Hoffmann wich became his most brilliant success on opera-stage for several years. He still is a member of the Ensemble of the Dresden State Opera where he was highly acclaimed for numerous other roles too, e.g. Ismaele in Verdi's Nabucco, Narrboth in Strauss' "Salome", Steuermann in Wagner's The flying Dutchmann, Walther in Tannhäuser and the title-role in Georg Friedrich Haendel's Belszar as well as roles in operas from the 20th century like Dallapiccola's Il Prigionero Reimann' Lear and Melusine. However his stage-repertoire also includes Max in Weber's Der Freischütz, Macduff in Verdi's Macberth and Cavardossi in Puccini's Tosca. As from 1995 until 1998 he appeared in guest-productions at Berne Theatre (Schwitzerland) where his roles included Barinkay in Johann Strauß' opera The Gipsy Baron and Offenbach's Hoffmann. At the Teatro Nacional de Sâo Carlos in Lisbon he appeared recently with Mussorgski's Boris Godounov. In 1999 he recorded Richard Strauss' opera Friedenstag conducted by Giuseppe Sinopoli for Deutsche Grammophon.