In her television career from 1951 to 1966, Isabel appeared most often on comedies, with an occasional drama (such as Perry Mason). Her first role on television was a protagonist on the 1951 version of Dick Tracy. She played the recurring character of neighbor Mrs. Boone in Meet Millie, one of the first of the sitcom hits for CBS in 1954. She was seen as private-school proprietress Mrs. Nestor during the final (1955–1956) season of Our Miss Brooks. She was also a regular comedic actor in 1952 on The Abbott and Costello Show, and from 1957-1962 on The Red Skelton Show.