His "Monument to Hiroshima" series (1963) used found objects cast in bronze sculptures to evoke the chaotic humanity of the Japanese city after its incineration by atomic bomb.
He joined and later directed Atelier 17, the intaglio studio founded in London and moved to New York at the beginning of World War II by its founder, Stanley William Hayter.
While primarily known as a sculptor working in bronze and clay, he created a portfolio of etchings by 21 artists (examples include Willem de Kooning, Jacques Lipchitz, and Peter Grippe himself) and 21 poets (including Frank O'Hara, Dylan Thomas, and Thomas Merton) in a work entitled 21 Etchings and Poems.
According to Bob Mattison, Marshall R. Metzgar Professor of Art History at Lafayette College, Easton, Pennsylvania, “Moving away from simply realist depictions in public monuments, Grippe and his colleagues embraced Cubism with its openwork multidimensional view of the world and Surrealist imagery drawn from the subconscious thus bringing American sculpture into the modern era.”[5] As Grippe's artistic and academic career progressed, he taught at several higher education institutions, including Brandeis University, where he was named the first professor of sculpture.
Grippe is also mentioned in a transcribed Smithsonian Institution interview in 2002 with Ruth Asawa in her San Francisco in which she discusses his technique and their associates during the period from 1946 to 1949.