John Opper became interested in art at a young age studying at the Cleveland Museum of Art before graduating high school and later at the Cleveland Art School and at the Art Institute of Chicago. During the summer of 1934 he studied under Hans Hofmann at the Thurn School of Art in Massachusetts. After relocating to New York he reconnected with Hofmann, studying with him again at his 57th Street school.
A founding member of the American Abstract Artists, Opper earned a living as a teacher, worked for the Federal Art Project, and was the business Manager for Art Front, the Journal for the Artists Union group. It wasn’t until his forst solo exhibition in 1937 that his career as an artist began to flourish.