He performed on the Chautauqua and Lyceum circuits until 1930, when he relocated to Detroit, Michigan, to narrate and act in commercial and industrial films.

"[4] Seeking better opportunities in Hollywood, Parnell and his wife moved to Los Angeles, California, where, helped by his red-faced Irish look of frustration, he immediately began to appear in films in roles such as policemen, doormen, landlords, and small town businessmen.

[9][10] In the 1950s, Parnell began to appear on television in dramatic shows and situation comedies in roles similar to those that he had played in films.

He portrayed William Bendix's factory foreman, Hank Hawkins, on The Life of Riley, and Bill Anders on five episodes of the ABC/Warner Brothers western series, Maverick.

In 1966 he portrayed Sheriff Blake in "Jury at the Shady Rest" on Petticoat Junction and in "Pig in a Poke" on Green Acres.

His final public appearance came in 1974, when he and his wife were interviewed by TV talk-show host Tom Snyder along with other residents of the Motion Picture Country Home and Hospital.