Upon the 1963 cancellation of this series, Conrad made a handful of Spanish and American films and toured with a nightclub act in Australia and Mexico City.
Cast as frontier secret agent James West in The Wild Wild West in 1965, Conrad brought home $5000 a week during the series' first season and enjoyed increasing remunerations as West remained on the air until 1969. There are those who insist that Wild Wild West would have been colorless without the co-starring presence of Ross Martin, an opinion with which Conrad has always agreed. The actor's bid to star in a 1970 series based on the venerable Nick Carter pulp stories got no further than a pilot episode, while the Jack Webb-produced 1971 Robert Conrad series The D.A. was cancelled after 13 episodes. When Roy Scheider pulled out of the 1972 adventure weekly Assignment: Vienna, Conrad stepped in--and was out, along with the rest of Assignment: Vienna, by June of 1973.
Conrad had success with 1976's Baa Baa Black Sheep, aka Black Sheep Squadron, a popular series based on the World War II exploits of Major "Pappy" Boyington.
In 1989's Jesse Hawkes, Conrad co-starred with his sons Christian and Shane.
Conrad has enjoyed success as a commercial spokesman and in the role of G. Gordon Liddy (whom the actor admired) in the 1982 TV movie Will, G. Gordon Liddy.
As can be gathered from the Liddy assignment, Conrad's politics veered towards conservatism; in 1981, he and Charlton Heston were instrumental in toppling Ed Asner and his liberal contingent from power in the Screen Actors Guild.
As virile and athletic as ever in the 1990s, Robert Conrad has continued to appear in action roles both on TV and in films; he has also maintained strong ties with his hometown of Chicago, and can be counted upon to show up at a moment's notice as a guest on the various all-night programs of Chicago radio personality Eddie Schwartz.