The games will form part of the Soccer Challenge to highlight the aims of Mandela Day and will take place at the Moses Mabhida Stadium in Durban on Mandela Day itself (July 18) and the Cape Town Stadium on July 21.
Announcing the games, Chief Executive David Gill said, "The training camp and matches in South Africa will be an important part of our preparations for the 2012/13 season and an excellent chance to renew our acquaintance with our loyal and enthusiastic fans in South Africa.
"Everyone has fond memories of the visits in 2006 and 2008 and of the exceptional organisation for the 2010 Fifa World Cup."
Charles Brewer, Managing Director for DHL Express Sub-Saharan Africa, said, "We are delighted to be delivering Manchester United's pre-season tour to South Africa.
"Using our global network we'll be supporting the team in their preparation for the Durban and Cape Town legs of the tour, ensuring that the team are ready to deliver success on the pitch ahead of the 2012/13 season."