A man known only as Robur (Price), shoots down and takes on board his flying ship Prudent (Hull), his daughter Dorothy (Webster), her fiance Evans (Frankham), all of whom were exploring a volcanic crater in their hot air balloon, along with US government agent Strock (Bronson), who had hired them to look for evidence of an eruption. The supposed eruption was caused by Robur working on his airship, who had also inadvertently broadcast a biblical passage over a voice amplifier, stirring religious fears among the citizenry of the nearby town. Robur has been traversing the globe in his airship, the Albatross, with a goal of forcing peace on the world by virtue of his superior military capabilities. He has a loyal crew of like-minded, equally fanatical idealists. The captives learn how his ship operates, and about his technical advances, including generation of electrical power by crossing "lines of magnetic force" (presumably created by the earth's own magnetic field). The captives wish to escape, but don't fully trust Strock, who appears at times to side with Robur. After saving Evans' life, Strock explains that his oath of loyalty to Robur was insincere, and that as a captive, he feels no compunction to behave as a gentleman.
After the airship is seriously damaged by a storm, the captives manage to rig the gunpowder in the airship's armory to explode, while the ship is anchored to the shoreline of an island for repairs. All escape down the anchor line except Strock, who follows while being shot at by the crew. First Strock, then Evans, work at cutting the anchor line, finally releasing the airship, which is damaged beyond repair moments later when the gunpowder explodes. Robur orders his crew to abandon ship, but they choose to ignore his final order, and gather in his quarters while he reads from Isaiah 2:4 (the well-known "Swords into Plowshares" passage), reminding them of their pledge to try to rid the world of war. The ship, along with Robur and his crew, crashes into the ocean and explodes, while the captives watch, injured but alive, from the shore.
The film was an attempt by American International Pictures to create a prestigious epic adventure along the lines of 1956's Around the World in 80 Days. While it boasted a larger cast and more location work than was then the norm for AIP - it was the studio's biggest budget picture to date - it still utilized stock footage, including the opening miniature shot of Elizabethan London from Laurence Olivier's Henry V as a stand-in for Victorian London, with the airship Albatross superimposed over the top. Additional scenes of the Albatross destroying both sides in a naval engagement are created in the same manner, with stock footage borrowed from the battle of Trafalgar scenes at the end of the film "That Hamilton Woman" (1941).
The script combined elements of both Jules Verne's novels, Master of the World, and Robur the Conqueror. Robur, genius, inventor and, in this instance, creator of the powered heavier than air craft Albatross, with his hand picked crew, chooses to use weapons of war to force the governments of the world to lay down their arms and live in peace.
The special effects crew included Wah Chang and Gene Warren.
It was originally announced that Price's co-star would be Mark Damon, his co-star from House of Usher. Shortly thereafter, Damon was replaced by David Frankham.
Henry Hull came out of retirement to appear in the cast.
Vincent Price is reported to have considered the role of Robur as one of his personal favorites.
According to an article in Filmfax magazine, a sequel to Master of the World, to have been called Stratofin, was considered by American International Pictures. A concept model of the Terror, Robur's new land-sea-air vehicle, was built (the article included a picture of the model, which reportedly did not survive). However, those plans were never carried out, possibly due to the manner in which Richard Matheson and his cohorts combined various Jules Verne story elements from both Robur novels, causing serious continuity problems from the first film to the second.