Born in Warsaw in 1954, he studied the double bass (with Alfred Wieczorek and Andrzej Mysiński) and composition (with Włodzimierz Kotoński) at the F. Chopin Music Academy in Warsaw. Thanks to a Witold Lutosławski grant, he continued his compositional studies abroad, with Isang Yun in West Berlin and Klaus Huber in Freiburg (1986–87). As a double bass player he focuses on the contemporary solo repertoire. He has performed in many European countries, Asia and the United States.
He is also active as an improviser, playing with musical ensembles such as Mud Cavaliers and Laterna. In 1999 his Concerto à rebours for violin and orchestra (1998) was recommended at the UNESCO International Rostrum of Composers in Paris.
He is also active in the field of promoting contemporary music and arts education. He ran several cycles of radio programmes introducing children into the world of new music, and co-operated with the Children’s Arts Centre in Poznań and the Okopowa Cultural Centre. He was Artistic Director of World Music Days in Warsaw in 1992. In 2004 he was invited as a lecturer to the Darmstadt Summer Courses for New Music.
His works have been commissioned by institutions, festivals and ensembles such as Warsaw Autumn, Polish Radio, Poznań Philharmonic, de ereprijs, the Darmstadt Summer Courses for New Music, Klangspuren in Schwaz, Klangforum Wien, Hiroshima Symphony Association, and others.
In 2013, Deutschlandfunk Köln Radio broadcast a retrospective of Tadeusz Wielecki’s music within its Atelier Neuer Musik series. Also in May 2013, his composition Ridge was performed by the China Philharmonic Orchestra during the Beijing Modern Music Festival.
He has served as Director of the Warsaw Autumn International Festival of Contemporary Music since 1999.
Selected works (since 1995): Id for orchestra (1995–96), Study of Gesture I for clarinet, piano and cello (1995), Study of Gesture II for piano (1997), Concerto à rebours for violin and orchestra (1998), Thèsis for solo flute (2000), Study of Gesture III for clarinet, trombone, piano, cello and double bass (2000), Credo, quia absurdum for tape and dancer (2001), Time of Stones for chamber ensemble amplified double bass (2002), Tafle for orchestra (2002), String Quartet (2004), The Whisper of Semitones for double bass and chamber ensemble (2004), Schwärme for symphony orchestra (2005), Hazard and Necessity for string quartet and electronics (2006), The Valley of Dry Water for chamber orchestra (2007), String Vibration for harpsichord (2008), Piano Concerto (2008– 09), Documentary Opera about the Round Table, new version of the documentary opera Knights of the Round Table (2009), At the beginning there was... for slammer, sampler and chamber ensemble (2009), Quartertones and half-shades for double bass, two percussions and trumpet ad libitum (2009), Gear Wheels, Springs and Modes for violin and guitar (2010), The thread is Spinning ... IV for double bass and chamber ensemble (2012), Subjective Model. Dramatised Form for viola, tuba, tape and informal group of performers (2012), Points of hearing for chamber ensemble (2012), The Little Shoemaker and the False King, chamber opera for children and adults (2013).