Pietersen will join the squad later on Monday as they prepare for Saturday's Test at the Nelson Mandela Bay Stadium.
Injuries to full-backs Zane Kirchner (knee) and Pat Lambie (ankle) in the first two Tests, as well as Frans Steyn's non-availability because he is getting married, has necessitated the call-up.
Pietersen, who had been struggling with a back injury, had been given the all clear by the Western Province medical team to join to Boks on Monday.
"Joe has always been part of our plans and also attended our final Planning Camp in Durban shortly before the England series started," explained Bok coach Heyneke Meyer.
"Injuries are part of the game and something you can't plan for, but we always knew Frans was not going to be available for this Test. Joe knows our systems and game plans and I'm sure he will slot in easily."
>>More young blood for the team, this is really interesting and doubt many (including myself) would have seen him being chosen over Gio.
