[1] Duszyński was born in Moscow to the family of Feliks (a civil servant and state administration official, activist of the Polish Red Cross) and Maria Duszyński who were evacuated from Poland right before the offensive of the German Army during World War I.

After the end of World War I, along with his parents he returned to Warsaw and then soon afterwards the family moved to Mińsk Mazowiecki, where he graduated in 1935 from I Gimnazjum Humanistyczne.

His stage career began just before World War II, with a debut on 25 July 1939 in the role of the minister's cousin in ("Geneva") in Polish Theater in Warsaw and then in Wilno, where he performed between 1939–41 at Theater on Pohulanka together with Hanka Bielicka and Danuta Szaflarska.

After the war he played in two popular films:Skarb and Zakazane piosenki, that have made him the first male star of the post-war Polish cinema.

His last major film role was as Józef Piłsudski in Śmierć prezydenta directed by Jerzy Kawalerowicz in 1978.