The theme song became a popular hit during the run of The Greatest American Hero. "Believe It or Not" entered the top 40 of the Billboard Hot 100 on June 13, 1981, eventually peaking at No. 2 during the weeks ending August 15–22, 1981, kept off the top spot by "Endless Love" by Diana Ross and Lionel Richie, and spending a total of 18 weeks in the top 40. On the Adult Contemporary chart, "Believe It or Not" went to number 3.[2] It also peaked at the number one position on the Record World chart.[3]
In the season 8 episode of Seinfeld titled "The Susie", an answering machine message featuring parody lyrics of "Believe It or Not" is a central plot point.[4] As a tribute to the Seinfeld episode, the song appeared in a 2021TV commercial for Tide that aired during CBS' telecast of Super Bowl LV on February 7, 2021 starring Jason Alexander, whose character George Costanza recorded the parody lyrics as his answering machine message.