Theron, one of the speakers at the official opening of the International Aids Conference in Durban on last evening, is South African by birth and started a foundation in 2007 to help prevent adolescents and young people becoming infected with HIV in ever greater numbers.
The 40-year-old actress, in an interview to The Guardian, said increased funding was very important in the effort to end AIDS.
"But at the same time I also think that there are very fundamental issues like stigma, and there's a racial part of it too that I think we haven't really talked about or people are too scared to talk about," she said.
Therons early and teenage years were lived in the shadow of a growing HIV epidemic in South Africa.
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"I have very vivid memories [of] being very young and being affected by what was happening. I don't think anyone at that time knew what it was and I think that was what was so incredibly scary. But it left quite an impression on me that stayed with me for the rest of my life," she said.
"As a South African that's very hard to un-know. Once you know that, you want to be a part of the solution somehow. I feel like from the very time I could remember, AIDS and HIV have had an impact on me.
"I'm talking about my early teenage years so this is before I was really travelling. But my parents were avid news-watchers and newspaper readers so that conversation was constantly happening in our house," she said.
The Charlize Theron Africa Outreach Project aims to help children and young people safeguard themselves against HIV.