A drummer. He is considered to be one of the leading jazz drummers in Europe. Over the past forty years of working as a drummer, composer and band-leader, he gained international recognition in a group of musicians and critics.

His musical education began in Krakow. In 1966 he graduated from State Musical High School, and in 1972 the State Higher School of Music. Then he mastered his skills in Berclee College of Music in Boston (USA) (graduated in 1975). Nowadays he is a respected pedagogue. He gives jazz workshops in many European countries (Poland, Hungary, Germany), Canada and South Africa. Since 1993 he has tought percussion and rhythm theory at the Jazz Faculty at Higher School of Music at Johannes Gutenberg University in Mainz, and in February 2009 he received the title of profesor of that university.

He made his debut in 1966 at Jazz nad Odrą Festival in Wroclaw with the band of Zbigniew Seifert. He worked with groups of leading Polish jazz musicians - Tomasz Stanko's quintet, a radio band of Jan Ptaszyn Wroblewski and Quartet of Zbigniew Namyslowski, with whom he performed in 1980 at the famous Village Vanguard club in New York. In the seventies he worked with bands from Germany and Austria, among others Radio Jazz Group Stuttgart, Zbigniew Seifert Variouspheres and Vienna Art Orchestra.

Since 1981, the artist has lived permanently in Germany. He came back to Poland after 12-years since announcement of martial law, for anniversary concerts for Zbigniew Namyslowski.

Over the last 28 years of residence in Germany he performed with: Polish Jazz Ensemble (Zadlo, Sendecki, Suchanek), Wolfgang Lackerschmid Connection Mallet and Heinz Sauer Quartet. He has collaborated with such musicians as Wolfgang Dauner, Karl Berger, Joachim Kühn, Ken Werner, Joachim Kaufmann, Jan Jarczyk, Jasper Van`t Hof, Bob Degen, Carla Bley, Dave Friedman, Frank Tusa, Rick Rosie, Steve Swallow, Albert Mangelsdorff, Woody Shaw, Kenny Wheller, Ack van Rooyen, Harry Beckett, Adam Pierończyk, John Tchicai, Dave Liebman, Charlie Mariano, Paul Heller and many others. Several years ago he formed his own band - Janusz M. Stefanski JazzArt.

Stefański has participated in numerous recordings for radio and television in Poland, the Czech Republic, Hungary, Austria, Switzerland, Belgium, Denmark, Germany and Canada. He has recorded over 60 albums and has appeared on over 100 major festivals around the world (Europe, Canada, India). He composed the music for three films for German television. In 2003 he was awarded the Jazz Award granted by the Ministry of Science and Art in Wiesbaden.

In addition to a purely artistic activities, he was the initiator, organizer and artistic director of the closing-concert of Book Fair 2000 in Frankfurt, and German-Polish Jazz Jamboree 2005 in Frankfurt, with the participation of thirty jazz musicians from both countries.