From 1988 to 1998, he was a professor of computer science, robotics, and art at Carnegie Mellon University, after which he joined Pixar in Emeryville, California.

At CMU and Pixar, with his colleagues he developed the methods and simulators used to model and render natural-looking cloth,[2][3] hair, water, and other complex aspects of modern computer animation.

[4] The paper "Snakes: Active Contour Models"[5] achieved an honorable mention for the Marr Prize in 1987.

[6] The 1987 paper "Constraints on deformable models: Recovering 3D shape and nonrigid motion"[7] was also a prize winner.

"[10] As senior scientist at Pixar, Witkin received a technical Academy Award in 2006 for "pioneering work in physically based computer-generated techniques used to simulate realistic cloth in motion pictures.