Aaliyah Allai from Raucall Secondary School in Brixton is a chartered accountant in the making.
She came second in the province's previously disadvantaged schools with six distinctions.
Allai, an 18-year-old from Mayfair, said even though she had expected to do well, making it to the top 10 was a blessing.
She said she knew she had aced English and mathematics because they were her favourite subjects, but was less certain about the others.
She gives credit for her success to her mother, who is raising her and four siblings single-handedly.
"I have always had support from my family, especially my mother and my teachers. They all believed in me and I guess that's what has motivated me to be the best I can be," she said.
She plans to study BCom Accounting at University of Cape Town next year.
Not only is Allai something of a genius, she has also spent most of her high-school life travelling the world because of her involvement in charity work and being a child rights activist.
When she was 12, she made the opening speech at the opening of the national children's parliament.
She has also attended the past four Third World Children's Summits and is excited that South Africa will be hosting the summit in Sandton next year.
"I will never stop participating in charity work, even when I'm all grown up and have a career.
"I've had the best time and have managed to achieve a lot as a child," she said.