Winfrey hails Mandela's "goodness and integrity", describing him as her "favourite mentor".
PIC: Oprah Winfrey poses on the red carpet next to a banner depicting Mandela, as she arrives to attend an event to mark 100 years since the birth of the anti-apartheid icon, at the University of Johannesburg, Soweto Campus, in Johannesburg. (AFP)
US television celebrity Oprah Winfrey on Thursday paid emotional tribute to Nelson Mandela as she prepared to host a star-studded concert in Johannesburg to cap celebrations marking 100 years since his birth.
Winfrey will co-host the Global Citizen festival on Sunday, where artists including Beyonce, Jay-Z, Cassper Nyovest, Ed Sheeran, Femi Kuti, Pharrell Williams, Chris Martin and Tiwa Savage will perform.
The concert is the climax of a year of events celebrating the centennial of Mandela's birth in 1918, and is part of a campaign to tackle poverty, child malnutrition and boost gender equality.
Winfrey hailed Mandela's "goodness and integrity", describing him as her "favourite mentor" as she spoke at a public debate at the Soweto campus of the University of Johannesburg.
"He was a man who could have sought revenge, but he was a man who sought reconciliation," she said, adding he "knew that when one of us is wounded all of us are bleeding."
Mandela was jailed under South Africa's apartheid regime. After being released in 1990, he led the country's transformation into a multi-racial democracy. He died on December 5, 2013 aged 95.
She said Mandela "could have actually crushed his opponents with his power but instead he choose to defeat them without ever" ever disarming them.
Oprah said the Mandela sought reconciliation instead of revenge
Former US president Barack Obama spoke in Johannesburg in July, delivering the flagship address of the "Mandela 100" celebrations, remembering the "wave of hope that washed through hearts all around the world" when Mandela was released from jail.
Tickets for the weekend concert were allocated to people who have taken part in the Global Citizen campaign.
The 64-year-old talk show queen spoke to hundreds of mainly women guests at an auditorium in Soweto, a township which was the hotbed of the struggle against apartheid.
The public debate was also attended by Mandela's widow Graca Machel and South Africa's former deputy president Phumzile Mlambo-Ngcuka, who is currently the head of UN Women.
"We all need to roll up our sleeves wherever you are whatever you can do and begin to build a new future," she said in her speech.
"In doing that you align with Madiba vision - both compassionate and practical," she said, referring to Mandela by his clan name.
Winfrey in 2007 founded a school in South Africa for girls from poor backgrounds to groom them into elite leaders.
Listening to the speech was Lumka Jwara, a 28-year old banker from the neighbouring township of Kagiso.
"She has done a lot for so many people, even indirectly, through her shows. Both she and Mandela are resilient, they have the ability to change other people's lives," said Jwara.