The 2011-2012 English Premier League runners-up face two mid-table South African Premiership clubs -- AmaZulu in Indian Ocean city Durban on July 18 and Ajax Cape Town on July 21 in Cape Town.
United then travel to China for a further pre-season fixture against local club Shenhua in Shanghai on July 25, two days before Premier League champions Manchester City face Arsenal in Beijing.
The Red Devils are the most popular foreign football club in South Africa and this will be their third visit after 2006 and 2008, and they went on to win the championship the following season on each occasion.
Manchester United director of communications Phil Townsend told the South African media that the three-time European champions would use the tour to blood new players.
"We use these tours to prepare players for the arduous season ahead and to introduce new players to the team and management. It is also an opportunity for our fans abroad to witness the team playing first hand," he said.
AmaZulu are coached by Swede Roger Palmgren and finished seventh last season while Ajax disappointed under Dutch handler Maarten Stekelenburg and came ninth after being pipped for the title the previous season.