The Lecture is hosted in association with the University of Pretoria at their Mamelodi campus. It is dedicated to the Mamelodi families who lost loved ones during the apartheid years. The Lecture honours their contribution to the struggle for democracy.
Speaking in a pre-recorded video message, Gates said he was honoured to have been invited to contribute to the conversation on how to create a better world.
Gates highlights the need for a new social pact across the globe to end protracted conflict, overcome intolerance and prejudice, improve access to healthcare and education, and reduce poverty and inequality.
The Nelson Mandela Annual Lecture is the Foundation's flagship programmes to honour its founder, Nelson Mandela, and to raise topical issues affecting South Africa, Africa and the rest of the world. It encourages both local and international dialogue - often about difficult subjects - as a means to address the multiple and complex challenges that face the world today. The Lectures are addressed by speakers who have made a significant contribution in their field of expertise.
Gates said the founding President of a democratic South Africa would be "remembered for generations to come for his courage, his vision and his relentless pursuit of equality and justice".
He said Mandela's legacy "lives on as a reminder that it's possible to solve big challenges".
Dr Ayo Ajayi, director of the Africa Team at the Bill & Melinda Gates Foundation, said, "Bill coming for the Mandela lecture and the AIDS conference is an indication of how important both South Africa and Africa is to the foundation. The Mandela lecture will show Bill's thinking about the role Africa can and is already playing in its own development. We hope the lecture will stimulate more debate about philanthropy in Africa and Bill's approach to development".