The show focused on a 4-foot-tall (1.2 m), purple alien from the Horsehead Nebula named Widget who could shapeshift (usually by spinning like a top into different forms, in early episodes he seems to still be getting used to his power). He and a group of young, human friends; brothers, Kevin, Brian and their teenage sister Kristine, would go through a number of adventures to protect the natural environment from those who wish to plunder or harm it. Later on they were joined by (fellow shapeshifter) Half-Pint, Widget's mischievous, overly-curious, hyperactive cousin. Widget is frequently accompanied by the Mega Brain, an extremely intelligent but somewhat clumsy being who appears as a floating head (with a transparent cranium) and floating hands.
The show was produced by Calico Creations to teach children about the dangers of pollution. Each episode would have Widget contending with a villain from either earth or outer space wishing to exploit Earth's environment or natural resources, like Dr. Dante, Mega Slank, and his evil twin, Ratchet. In this respect, Widget, the World Watcher is very similar to Captain Planet and the Planeteers, both heroes attempting to save the Earth from ecological harm. Even occasionally, combatting an entity/being created/mutated from copious pollution. For example, in one episode Widget battled a fellow shapeshifter; a sentient but hostile life form, disguised as a toxic ooze/slick, who was contaminating our beaches and oceans.
Widget ran for 65 episodes, 13 in the first season and 52 in the second season.