Dag Jensen was born in Horten, Norway, and began studying bassoon with Robert Rönnes at the age of 11. He later studied at the Norwegian Academy of Music in Oslo with Torleiv Nedberg. He obtained his first position in an orchestra in the Bergen Philharmonic Orchestra at only 16 years old and was promoted to soloist of the same orchestra. He continued his training with Professor Klaus Thunemann in Hanover.

He was a soloist in the Bamberg Symphony Orchestra from 1985 to 1988 and in the Cologne Radio Symphony Orchestra from 1988 to 1997. He also participated in the Saito Kinen Festival Orchestra and the Mito Chamber Orchestra, and in both he worked under the artistic direction of Seiji Ozawa. Between 2003 and 2006, Jensen was chosen as principal bassoonist when Claudio Abbado founded the “Luzern Festival Orchestra”.

Dag Jensen received first prize in the Norwegian Youth Music Competition and twice won the coveted ARD Music Competition in Munich, in 1984 and 1990.

His numerous appearances as a soloist with renowned orchestras include, among many others, the Bavarian Radio Symphony Orchestra, the Cologne Radio Symphony Orchestra and the South German Radio Symphony Orchestras, the Mito Chamber Orchestra, Japan, the Royal Swedish Chamber Orchestra, Camerata Academica, Salzburg, the English Chamber Orchestra, the Würtemberg Chamber Orchestra, the KBS Symphony Orchestra of Seoul, the Oslo Philharmonic Orchestra, the BBC Symphony Orchestra of Manchester, the Prague Symphony Orchestra and the Norwegian Chamber Orchestra with conductors such as Seiji Ozawa, Jeffrey Tate, Sandor Vegh, Serge Baudo, Christopher Hogwood and Iona Brown have taken him all over Europe and Asia.

Chamber music plays an important role in his musical life, and he is a member of the Sabine Meyer Wind Ensemble and the Villa Música Ensemble. He is also a regular guest at music festivals such as «Spannungen» in Heimbach, Schubertiade, Schwarzenberg and many others.

His artistic career is well documented on CD, with piano accompaniment, as well as chamber music works and bassoon concertos.

Dag Jensen was a professor at the Hanover University of Music and Drama from 1997 to 2011, and since 2011 he has been a professor at the University of Music and Performing Arts in Munich. He is also a professor at the Norwegian Academy of Music in Oslo.