Chibi-Robo is cleaning the exterior of a space station when his companion Telly reminds him to take a break. During the break, Chibi-Robo watches television and discovers that a lot of the natural resources on Earth have vanished, disappearing because of invading aliens. The pair are suddenly disturbed by a cluster of aliens, known as the Gyorians, who are making their way towards Earth. As such, they both set out in the "Chibi House" to combat the alien invasion.: 12 During the adventure, Chibi-Robo travels to all continents of the world to reclaim the stolen resources and defeat the alien robots that guard their specific continent.
The two eventually head to Antarctica where the Aliens' Mothership is located. Chibi-Robo promptly destroys the Mothership, but an orb escapes the wreckage and heads towards a metropolitan city in Asia. The orb then transforms into a large monster named "The Mega-Mech Menace" and starts to wreak havoc. To combat the monster, Telly and Chibi construct a giant named "Giga Chibi-Robo"; the two giants battle each other until Chibi-Robo deactivates the monster and destroys it, prompting both Chibi and Telly to head back to the station