On April 14, 1930, Ripley brought "Believe It or Not" to radio, the first of several series heard on NBC, CBS and the Mutual Broadcasting System. As noted by the website Ripley On Radio, Ripley's broadcasts varied in length from 15 minutes to 30 minutes and aired in numerous different formats. When Ripley's 1930 debut on The Collier Hour brought a strong listener reaction, he was given a Monday night NBC series beginning April 14, 1930, followed by a 1931–32 series airing twice a week. After his strange stories were dramatized on NBC's Saturday Party, Ripley was the host of The Baker's Broadcast from 1935 to 1937. He was scheduled in several different 1937–38 NBC timeslots and then took to the road with popular remote broadcasts. See America First with Bob Ripley (1938–40) on CBS expanded geographically into See All the Americas, a 1942 program with Latin music. In 1944, he was heard five nights a week on Mutual in shows with an emphasis on World War II. Romance, Rhythm and Ripley aired on CBS in 1945, followed by Pages from Robert L. Ripley's Radio Scrapbook (1947–48).
Robert Ripley is known for several radio firsts. He was the first to broadcast nationwide on a radio network from mid-ocean, and he also participated in the first broadcast from Buenos Aires to New York City. Assisted by a corps of translators, he was the first to broadcast to every nation in the world simultaneously.
As the years went on, the show became less about oddities and featured guest-driven entertainment such as comedy routines. Sponsors over the course of the program included Pall Mall cigarettes and General Foods. The program ended its successful run in 1948 as Ripley prepared to convert the show format to television.