He was born in Posen, Prussia (German Empire), now Poznań, Poland, as a son of Polish parents, and emigrated to the United States at the age of two.
[2] From 1925 to 1926 he studied at the School of the Art Institute of Chicago, In 1930 he won the Logan Medal of the Arts, then moved to New York City to take classes at the National Academy of Design with George Luks and at Columbia University, where he studied logic and philosophy.
He was a participating artist at the documenta II in Kassel 1959 and at the Venice Biennale in 1960.
[3] Roszak's sculpture, at first closer to Constructivism and displaying an industrial aesthetic, changed after around 1946 to a more expressionistic style.
Roszak sculpted the 35-foot (11 m) gilded aluminum eagle on the pediment of the former US Embassy in Grosvenor Square, London.