Anadolu news agency reported that the decision was made by the Istanbul governor's office Sunday, citing an anonymous security official.
Hatice Cengiz, a Turkish national, waited for Khashoggi outside the Saudi consulate in Istanbul on Oct. 2, where he was to get papers for their planned marriage. She alerted authorities after the writer did not emerge from the building.
Saudi officials on Saturday confirmed that he died, after denying knowledge of his circumstances for over two weeks.
The report did not say why Cengiz was given police protection.
The Associated Press
More about: JamalKhashoggi