Wynn was born into a family of show business. His father, the comedian and clown Ed Wynn, was a well known actor in television and cinema (including the Uncle Albert in Mary Poppins ). Keenan Wynn began his career in the 1930s in the theater, 1935-1943, he played in several Broadway productions. Beginning of the 1940s, he received first roles in the film, until his death, he was a busy actor. Noticed appearances had Wynn in movie musicals, so among other things in Annie Get Your Gun and Kiss Me, Kate! or The Golden Rainbow beside Fred Astaire. Wynn also played frequently supporting roles in westerns, as in Play me the song of death.
A cult role was that of schurkigen financial magnate and investor Alonzo P. Hawk, the Keenan Wynn embodied in the 1960s and 1970s in three Disney films, all directed by Robert Stevenson. In the first two of these films, The Flying Pauker and its sequel The Pathfinder 's can not leave his father Ed Wynn played with. In addition, Wynn was seen in the course of his career in countless television movies and series, so among other things, the beginning of the 1980s on the soap opera Dallas as Willard " Digger" Barnes the opponent of John Ross sr. " Jock " Ewing ( Jim Davis).
By 1959 he had submitted his autobiography with the significant title Ed Wynn 's Son with James Brough. Keenan Wynn died at age 70 in Brentwood, California from cancer. His son, Tracy Keenan Wynn is a screenwriter.