Kaffir Boy is Mark Mathabane's autobiographical recounting of his life growing up in apartheid-era South Africa, and his struggle to overcome the poverty and racism that he faces as a child. As a young boy, Mark's family struggles to afford to send him to school, but his mother is insistent that he receives an education. While he faces unjust punishment by the school administration for struggling to afford his education, Mark still excels at school and receives a scholarship for secondary schooling.

During his childhood, he faces extreme racism and discrimination and learns that white folks are a source of oppression and pain. However, once Mark's grandmother obtains a job as a gardener at a kindly white family's house, Mark is introduced to a different kind of white person. The Smiths send books and a tennis racket home for Mark. After receiving the tennis racket, Mark soon discovers that he enjoys and also excels at tennis. He finds a black tennis player to train him in Alexandra and soon joins his all-black tennis high school team. Mark meets Wilfred Horn, who is the owner of the Tennis Ranch, a country-club-esque ranch that is accessible only to whites. However, Horn allows Mark to attend the ranch, as Mark is a very skillful and promising tennis player.

At the Tennis Ranch, Mark meets Stan Smith, who is interested in seeing Mark advance through the levels of tennis tournaments. Smith pays for Mark's entrance fee into a tennis tournament, the Breweries's Open. The Open is technically accessible to black players, however, black tennis players boycott the tournament to resist the apartheid government's attempt to appear non-oppressive of black people. Mark, in an act of betrayal to black players and his black community, decides to play in the tournament. As a result, he is shunned from his black tennis community and banned from playing with all-black teams and in all-black tournaments. Mark, however, decides that he is going to focus on his personal advancement and continues pursuing his dreams of escaping from racist South Africa. Through his prestigious connections and skills, Mark is accepted on a tennis scholarship to a college in South Carolina, and he finally flees apartheid South Africa.