Mikuláš Jelinek gave hundreds of recitals in many countries included China. As a soloist he has cooperated with pianists in Slovakia (Eva Fischerová-Martvoňová, Rudolf Macudzinski, Michal Karin-Knechtsberger, Daniela Varínska, Marián Lapšanský, Helena Gáfforová and others), Czech Republic (Marie Knotková, Eva Bernáthová, Pavel Kuchař, Dagmar Baloghová), Sweden (János Solymos, Esther Bodin), Germany (Günther Ludwig, Christine Scheuermann, Ingrid Heiler), and the former Soviet Union (Jekaterina Fuchsovova).
He was a member of several chamber ensembles in Slovakia. Abroad he was the first violinist of Gürzenich-Quartett Köln Quartet (with Franz Neumann, later Geoffrey Wherton, Ulala Seo, Daniel Cahen), and he was an artistic director of Solistenvereinigung des Gürzenich-Orchestra Köln.
As a soloist he cooperated with leading domestic and foreign orchestras under many conductors (Václav Talich, Ľudovít Rajter, Tibor Frešo, Kornel Schimpl, Zdeněk Bílek, Roman Skřepek, Otakar Trhlík, Jiří Pinkas, Václav Jiráček, Rudolf Vašata, Viktor Dubrovskij, Helmut Koch, David Shallon and many others).
His artistic activity is also rich in playing with orchestras: Bratislava Radio Symphony Orchestra (in 1945 – 1947), Slovak Philharmonic (1949 – 1951), Sarrländische Rundfunk Saarbrücken, Germany – first concert master (1965 – 1966), Sveriges Radio Stockholm, Sweden – first concert master (1966 – 1968) and Gürzenich-Orchester der Stadt Köln, Germany – first concert master (1967 – 1990).
As a pedagogical and artistic advisor he worked in German orchestras: Siegerlandorchester, Hilchenbach (1971 – 1983), Bayer Sinfoniker Leverkussen (1972 – 1977) and Rheinisches Kammerorchester Köln (1977 – 1981).
From 1951 – 1965 as pedagogue of violin at Academy of Performing Arts in Bratislava he prepared for praxes 15 graduates. In Cologne he taught at the Rheinische Musikschule and privately had a total of 80 students (e. g. Boris Kucharský, who works in Munich – son of leading Slovak tenor Andrej Kucharský). As lecturer of violin master classes he was invited into Rünö, Sweden (1966 – 1968), Piešťany (1992, 1993), Žilina (1991), Weikersheim, Germany (1993), Debrecen, Hungary (1996), Graz, Austria, and from 1996 – 1999 worked as consultant of the Summer Workshops of Chamber Music in Žilina. He was a member of international juries: of the competition Stephan Ruha (Romania – Satu Mare), competition “Gradus ad Parnassum” in Innsbruck, Austria (2001), international competition of Jaroslav Kocián in Ústí nad Orlicí (2002) and Tallin, Estonia (2002).
Since 1974 he has been a member of the European String Teachers Association (ESTA), and from 1990 – 1999 was a member of the Central Board. For this Association he led a number of lessons and seminars at home and abroad (Freiburg, Berlin, Stockholm, Bern, Vienna, Trieste, Hannover, Cologne, Budapest).
His initiative led to the establishment of the Slovak section of ESTA (in 1991), which operates since 1992. He is a permanent member of its board, and from 1995 – 2003 was president. Since 2004 he is a vice president of the Slovak section of ESTA. He is also a member of the Board of the Music Teachers Association of Slovakia.
Currently Mikuláš Jelinek is focused on pedagogical, methodical and organizational activity.