According to the Sunday Times, the child was born in February 2008 to an unemployed Johannesburg couple, who was traced this week.
However, the reason for the search is not known as neither parents would speak to the newspaper.
The little girl, whose name is unknown has been photographed numerous times over the years with the celebrity couple and their two daughters.
When questioned in the past, Rock’s PR agents have simply said she was the daughter of a family friend from South Africa, but questions have been asked for years whether the little girl was in fact adopted by the Rocks.
The has apparently been no hint that she had been adopted but according to the newspaper, the recent activities by investigators to trace the girls biological parents could suggest that formalities are under way.
The mystery child first emerged in early 2010 when Rock was seen carrying her in New York. At the time, the New York Post asked if the comedian had a "secret".
But days later other publications reported that the child was South African and that she was a family friend. Not once has she ever been named.
This first sighting did initially spark rumours of a possible love child, which came after a 2007 rumour that he was the father of a love child after an actress filed a paternity suit claiming Rock was the father of her son, but DNA testing proved he wasn’t.