Terje Mikkelsen studied at the Norwegian State Music Academy and at the Sibelius Academy in Helsinki (Jorma Panula's class). During his career, he has been the chief conductor and the art director of the Ukrainian State Orchestra, Thuringen Philharmonie and the Latvian National Symphony Orchestra and also the principal guest conductor of the Lithuanian State Symphony Orchestra. He has worked with the Cologne Radio, the Belgian Radio and the Hamburg Radio Orchestras, with the Warsaw Philharmonic, and other prmonent ensembles. His tour routes have embraced Germany, Spain, the Netherlands, Sweden, Norway, Lithuania, Estonia, Japan, etc.
In 2005, Mikkelsen made a European tour with the Shanghai Symphony Orchestra, a year later becoming its principal guest conductor. Since 2001, he has been professor at the College of Music, the Mahidol University in Bangkok.
Over the past seasons Mikkelsen has taken part to the Tchaikovsky Symphony Orchestra's series of public concerts "Music for all" and to its other programmes. At the end of the 2007-2008 season, he was invited together with the orchestra to participate in the closing concert of the 3rd Rachmaninov International Piano Competition in Los Angeles.