He studied at the Slade School of Fine Art (part of the University of London). In 1945, he moved to New York City, where he graduated from New York University Institute of Fine Arts with a Ph.D. in 1960, and taught life drawing at the Parsons School of Design. He taught at the City University of New York and the University of Pennsylvania as Benjamin Franklin Professor of the History of Art, from 1975 to 1991
He was professor of the History of Art at Hunter College. He is known for his work in several areas of Art History, notably Renaissance art and Modernism. From 1995-96, he was a professor at Harvard University.
In 1972, Steinberg introduced the idea of the "flatbed picture plane" in his book, Other Criteria, a collection of essays on artists including Jackson Pollock, Pablo Ruiz Picasso, Phillip Guston, Robert Rauschenberg, and Willem de Kooning.
The whole of the Summer, 1983, issue of October was dedicated to Steinberg's essay The Sexuality of Christ in Renaissance Art and in Modern Oblivion, later published as a book by Random House. In that essay, Steinberg examined a previously ignored pattern in Renaissance art: the prominent display of the genitals of the infant Christ, and the attention drawn again to that area in images of Christ near the end of his life.
In Tom Wolfe's 1975 book, The Painted Word, Steinberg was labelled one of the "kings of Cultureburg" for the enormous degree of influence that his criticism, along with that of other "kings," Clement Greenberg and Harold Rosenberg, exerted over the world of modern art at the time. However, Steinberg, who originally trained as an artist but earned a PhD in Art History, moved away from art criticism, concentrating on academic art-historical studies of such artists and architects as Borromini, Michelangelo, and Leonardo da Vinci. His collection of 3,200 prints is held at the The Leo Steinberg Collection, Blanton Museum of Art, University of Texas, Austin.[5] His papers are held at the Getty Museum.