The actress was 15 when her alcoholic dad shot through the door of the room where she was hiding with her mum.
"None of those bullets ever hit us, which is just a miracle. But in self-defence, she ended the threat," she told NPR.
She added: "The more we talk about these things, the more we realise we are not alone in any of it."
Charlize grew up on on a farm near Johannesburg in South Africa with her mum Gerda and dad Charles.
She described her dad as a "very sick man" and said living with an alcoholic was a "pretty hopeless situation".