Witkin entered Saint Martin's School of Art in London in 1957 and studied under Sir Anthony Caro and alongside artists including Phillip King, William G. Tucker, David Annesley, and Michael Bolus.

His piece, Nagas, was included in the seminal 1966 exhibit, "Primary Structures" at the Jewish Museum in New York representing the British influence on the "New Art" anchored by Anthony Caro.

At Bennington College, Bennington, Vermont, Witkin worked with a community of artists known as "the Green Mountain boys" who either taught at the school or were part of the local arts community, including notables such as painter Kenneth Noland, Helen Frankenthaler, Larry Poons, Paul Feeley and Jules Olitski and art critic Clement Greenberg.

Here he discovered a process of pouring molten bronze into wet sand on the ground to create organic appearing forms.

By assembling these forms he engaged in "...creating language out of the behavioral flow of metal, wresting order from chaos" as he is quoted as describing the process in his obituary at The Times Online website.

During his career Witkin also received the following awards: State of New Jersey Art Achievement Award, Burlington County College Foundation; Adolph and Esther Gottlieb Foundation Grant; New Jersey State Council on the Arts Grant and in 1981 a Guggenheim Fellowship.