He began his career at age 15 in the radio program, That Brewster Boy, before moving on to a career in film and television. He is best known as the first actor to play the part of "Darrin Stephens" in the 1960s sitcom Bewitched, which we left in 1969 because of a delbiliatating spinal injury suffered a decade earlier during the filming of They Came to Cordura. York was replaced in the TV series by actor Dick Sargent.
York had previously had a major role in the 1960 classic, Inherit the Wind, in which he played the young teacher charged with teaching the theory of evolution and defended by Spencer Tracy's character.