Flavin portrayed Sam Cooper in the 1958 episode, "The Ed Church Case", of the CBS crime drama series, Richard Diamond, Private Detective, starring David Janssen. In 1959, he guest starred as Big Dan Girod in the episode, "Invitation to a Murder", on the ABC/WB detective series, Bourbon Street Beat, starring Andrew Duggan. In 1960, Flavin appeared in The Twilight Zone episode "A Passage for Trumpet".