Crazed street preacher Brian David Mitchell and his wife Wanda Barzee kidnapped Smart from her bedroom on June 5, 2002, when she was just 14. In the next nine months, she was tied up, repeatedly raped and threatened.
"I mean, here I was, a 14-year-old girl, ripped from my family, from my friends, from the people I loved," she says in the interview, set to air Friday at 10 pm on NBC. "Being raped every day, not knowing when I'd be able to eat next, not knowing when I'd be able to drink next. And being chained to a tree."
Though Smart has never spoken to the media about the specifics of her months-long ordeal, she sat down Vieira ahead of the Tuesday release of her memoir, "My Story."
Smart, whose testimony put Mitchell and Barzee behind bars, says she "didn't feel human" during her abduction.
"I don't think there's anything worse you can do to a child."
Smart has since founded the Elizabeth Smart Foundation, which works to prevent violence towards children.