Terje Mikkelsen was born in Norway in 1957. He studied at the Norwegian State Music Academy, and with Jorma Panula at the Sibelius Academy in Helsinki, Finland, where he received his diploma in orchestral conducting in 1989. From 1984 he also studied with Mariss Jansons, with whom he collaborated closely both in St. Petersburg and Oslo until 1991.

From 1989 to 1995, Terje Mikkelsen conducted the Ukrainian State Orchestra in Kiev, and in 1993 the orchestra appointed him Chief Conductor and Music Director. From 1990 to 1995 he was Principal Guest Conductor of the Lithuanian State Symphony Orchestra, and in 1997 Terje Mikkelsen became the Chief Conductor and Music Director of the Latvian National Symphony Orchestra in Riga. From 2001 to 2005, he was the orchestra's Chief Guest Conductor. During Mikkelsen's long period of work with the LNSO, they have toured Germany, Holland, Sweden, Norway, Japan, Spain and Belgium, performing more than 70 concerts. In 1999 he was appointed Chief Conductor and GMD of Thuringen Philharmonie Gotha-Suhl, a position he held to 2004. With this orchestra he has toured France, Spain, Thailand and Germany.

Terje Mikkelsen appears as conductor on tour with the Czech National Symphony Orchestra in March 2011

Mikkelsen's collaboration with the Lativan National Symphony Orchestra has resulted in more than 20 CD recordings, including three discs of music by Johan Svendsen, as well as three discs by Johan Halvorsen. In 2009, Mikkelsen and the LNSO released two CDs of Norwegian music which received fantastic reviews from all over Europe.

Since 2001, Mikkelsen has been visiting professor at the college of music of the Mahidol University, Bangkok.He appears regularly with the St. Petersburg Philharmonic and the Moscow Radio Orchestra, and has conducted such renowned orchestras as the Warsaw Philharmonic, Cologne Radio Orchestra (WDR), Hamburg Radio Orchestra (NDR), Rotterdam Radio Orchestra, Belgian Radio Orchestra, BBC National Orchestra of Wales, Opera Bastille Orchestra and the Philharmonia Hungarica. Mikkelsen has conducted in most of the important halls in Europe, including the Berliner Philharmonie, Concertgebouw Amsterdam, Munich Am Gasteig, Cologne Philharmonie, Auditorium National (Madrid) and many more. In 2006, Terje Mikkelsen was appointed Principal Conductor of Shanghai Symphony Orchestra, a position he held until 2009.

Since 1993, Terje Mikkelsen has worked regularly with the Tchaikovsky Symphony Orchestra of Moscow Radio, being the orchestra's Principal Guest Conductor since 2009. In June 2010, he took the orchestra to the north of Norway to perform at the festival in Harstad, and in October 2010, he toured the UK with the Tchaikovsky Symphony Orchestra of Moscow Radio, performing to concert halls packed with enthusiastic audiences and receiving much critical acclaim. Reviewers described Mikkelsen's conducting as "immensely compelling and dramatically powerful" and his control of balance and texture as "masterly". Equally at home with both unfamiliar works and old favourites, he gave "a blistering whirlwind of a performance" of Ole Olsen's Asgaardsreisen in Nottingham, yet drew from the Tchaikovsky Symphony Orchestra "a lushly played, polished performance of the old warhorse", Tchaikovsky's Fifth Symphony, in Sheffield.

2010 was a busy year for touring: Terje Mikkelsen also toured Spain with the Academy of St. Martin in the Fields. In 2011, he will be recording and touring with the Munich Radio Orchestra and the Czech National Symphony Orchestra.