The singer was interviewed for a special recording of the comedienne's Chelsea Lately talk show.
Barbados-born Rihanna, 23, told Chelsea how shocked she was at the lack of black people in Australia.
Chelsea quipped she had only seen 'three-and-a-half' black people during her week-long work trip Down Under to record three of her shows.
Chelsea had her right foot bandaged after she injured it during a visit to her gym back home in America.
During the recording of the show at Sydney's Foxtel studios, Chelsea was clearly in some discomfort.
She had to sit whilst signing copies of her books for fans then at the end of the show she limped off with the help of an assistant.
Rihanna is in Australia for her Last Girl On Earth tour.