Ernst Hacker was born in Vienna of Jewish heritage. He studied art at the Academy there and engineering at the Institute of Technology. He fled Vienna in 1938 to escape the Nazi regime.

He came to New York, where he studied painting at the American Artists School, while supporting himself by working as a designer and letterer. At that time he began his lifelong production of woodcuts.

He was drafted into the American Army and eventually was stationed in Japan, where he met a group of modern Japanese printmakers. He was invited to join their group and exhibited with them in Tokyo.

When he returned to New York, he exhibited color woodcuts influenced by the modern Japanese color technique.

Hacker decided to study city planning and in 1949 received a master's degree in the subject from Harvard. He was awarded two consecutive Fulbright grants to research reconstruction and city planning in postwar Italy. On his return to the United States, he became Assistant Chief City Planner for the City of New York, all the while continuing to produce woodcuts and paintings.

In 1974, he settled in Florence, Italy, and dedicated himself entirely to his work. He died there in July 1987, leaving a large body of work of originality and quality.