The series takes place in an alternate universe called "Bushworld", where the sinking of the Titanic never happened, indirectly resulting in the United States of America being destroyed (except Hollywood, which became an island), Australia becoming the world's superpower, and Nicole Kidman becoming its Queen.

Possessing no powers and a simple costume, which is apparently enough to hide his identity, Kevin encounters a variety of evildoers that wish to do harm to his town.

Kevin is joined by his family who put up with his misadventures including his down-to-earth wife Vicky, and his 14-year-old twin children, a popularity-obsessed daughter Alison and a nerdy son Liam who secretly possesses psychic powers.

[2][3] In October 2022, Jemaine Clement, Rachel House and Jarrad Wright joined the cast, with Miranda Otto and Hugo Weaving announced to be making guest appearances.

The website's critical consensus states: "While Koala Man can feel like a hodgepodge of quirky ideas, its distinctive Australian identity gives it a pungent personality.