Winfrey, 59, had interviewed Mandela in 2000 about his 27-year prison sentence for opposing South Africa's apartheid government and his later rise to the country's presidency, reported Digital Spy.
The chat show host shared her recollections of her meeting with Mandela on her Instagram account.
"One of the great honours of my life was to be invited to Nelson Mandela's home, spend private time and get to know him. He was everything you've ever heard and more - humble and unscathed by bitterness. And he always loved to tell a good joke.
The anti-apartheid leader, 95, died at his home in Johannesburg, South Africa on December 6.