It is commonly confused with the Juno II launch vehicle, which was derived from the PGM-19 Jupiter medium-range ballistic missile.

Developed as a part of the Explorer Project, the original goal for the launch vehicle was to place an artificial satellite into orbit.

Following the Soviet Union's launch of Sputnik 1 on October 4, 1957 (and the resulting "Sputnik crisis") and the failure of the Vanguard 1 launch attempt, the program received funding to match the Soviet space achievements.

The launch vehicle family name was suggested in November 1957 by Jet Propulsion Laboratory (JPL) Director Dr. William Pickering, who proposed the name Juno, after the Roman goddess and queen of the gods, as well as for its position as the satellite-launching version of the Jupiter-C.

A fourth stage would have allowed the nose cone to overshoot the target and enter orbit.