His father was a Lemko of Greek Catholic rite and came from Odrzechowa in the Sanok district, his mother Anna Harnlender was a Pole with German roots.

[2][3] Nowosielski designed and erected the Church of the Birth of the Blessed Virgin Mary in Biały Bór.

In 1993, he received the Commander's Cross of the Order of Polonia Restituta[4] and was also awarded a prize by the Polish cultural foundation Wielka Fundacja Kultury.

[5] In 2022, a unique ceramic mosaic depicitng St Francis of Assisi by Nowosielski created in 1980 was discovered in the Warsaw district of Izabelin and added in 2023 to the register of cultural property due to its artistic and historic significance.

[7] In December 2023, he was the central figure of the exhibition "The Art of Seeing: Nowosielski and Others" organized at the Royal Castle in Warsaw.