The programme was first broadcast in 1964 with The World of Buckminster Fuller which explored the theories and structures of inventor Richard Buckminster Fuller and included the Horizon mission statement, The aim of Horizon is to provide a platform from which some of the world's greatest scientists and philosophers can communicate their curiosity, observations and reflections, and infuse into our common knowledge their changing views of the universe. There have been over 1000 episodes made and broadcast.
In the 1960s, Horizon was a magazine format with three or four items per episode and each episode varied in length.
Until early 2008, the length was standardised at 50 minutes, which was extended in the later half of 2008 to 60 minutes. Some episodes are adapted from documentaries by other broadcasters such as PBS's NOVA, and episodes of Horizon are in turn adapted by PBS and other broadcasters around the world. Michael Ambrosino, while serving a year-long fellowship with the BBC, was inspired by Horizon and went on to create the long-running NOVA series on the same model.