The title sequence shows the main five regular characters over a white background. In Series 3, it was amended to include Epponnee-Rae and Cujo. The five regular cast members are then credited over aerial shots of suburban houses. Szubanski is credited as "Special Guest Star," despite appearing in every episode. The theme song is "The Joker," performed by Gina Riley. A re-recording of it debuted in the telemovie opening sequence and has continued into Series 4.

Who sings the joker is me kath and kim? Let's have some stream of consciousness first.
The relevant information to answer the above question is: The theme song is "The Joker," performed by Gina Riley. So, the answer is Gina Riley.