At the age of 9 Jukka Harju found the horn and two years later he performed Mozart’s Horn Concerto in Eb KV447 at a concert in Dublin broadcasted for TV by European radio stations. The blitz start went on to the studies in the Sibelius-Academy in Helsinki with Kalervo Kulmala and later in Vienna University for music and arts with Roland Berger, principal horn of Vienna Philharmonic Orchestra. Harju was sought after by the Finnish leading orchestras as well as the EU Youth Orchestra and Gustav Mahler Youth Symphony Orchestra led by Claudio Abbado.
Harju has succeeded in several music competitions. By winning the 2nd Lieksa International horn competition (Holger Fransman in memoriam) he was nominated as a Brass player of the year 2006 in Finland.
Since 2008 Harju has led the Finnish Radio Symphony Orchestra's horn group. Before that he was a member of Tampere Filharmonia and Helsinki Philharmonic Orchestra. On the side he has appeared abroad as a guest principal horn: in l’Orchestre Philharmonique de Radio France, Swedish Radio Symphony Orchestra, Royal Stockholm Philharmonic Orchestra, Oslo Philharmonic Orchestra, Bamberger Symphoniker, Chamber Orchestra of Europe and Comics Oper Berlin.
As a horn soloist Harju has performed more than 50 concerts, including his home orchestra FRSO, Helsinki Philharmonic Orchestra, Lahti Sinfonia, Tapiola Sinfonietta, Ostrobotnian Chamber Orchestra, Oulu Sinfonia, Kymi and Pori Sinfoniettas, Virtuosi di Kuhmo, St Michel Strings, Vaasa, Kemi and Joensuu City Orchestras, Tallinn Chamber Orchestra, Dala Sinfonietta, Haydn Orchestra Bolzano etc.
If classical and romantic era repertuar is on his main focus, he is familiar as well with fresher concerto's, like Wolfgang Plagge, Per-Henrik Nordgren and premieres written for him: Kirmo Lintinen Concertino (2008), Aulis Sallinen's Five female portraits for horn, soprano and orchestra (2013) and Osmo Tapio Räihälä's Horn Concerto (2016).
As a chamber musician, recitalist and master class teacher Harju has played and taught in Italy, Germany, UK, Lithuania, Sweden, Norway and Iceland. As a chamber musician he has performed abroad from Japan to United States, even in Africa.
Harju has been entrusted with the jury in the 4th Lieksa international horn competition (Holger Fransman in memoriam) and the jury for the Verbier Festival Orchestra auditions. Year 2010 Harju hosted the 18th Nordic Horn Seminar in Turku, Finland. After he worked as a guest teacher in Metropolia University for applied sciences he has taught in Sibelius Academy at the University of Arts.
When not playing, Harju’s time is devoted to compositions, arrangements and work as a freelancer director. At the end of his film studies he represented Finland in the student jury of the 38th International Television Festival Golden Prague. As a director Harju got the KOURA nomination for the best music program for TV in year 2007, produced by the Finnish Broadcasting company YLE (Teema/YLE TV1). "Meta4 - inner voices" was broadcasted by the television stations abroad.