The London Irish centre comes in at No 13 in place of Manusamoa Tuilagi, who switches inside for Brad Barritt in a side showing five changes – two positional – from the one that started the first Test.
Toby Flood replaces Owen Farrell at fly half, Ben Foden moves to full back for the injured Mike Brown and David Strettle comes on to the left wing.
The pack remains the same while there are changes on the replacements’ bench, where Alex Corbisiero gets his first chance in the Castle series, in place of Paul Doran Jones, while Alex Goode takes over from Toby Flood.
England Head Coach Stuart Lancaster said: “I am delighted for JJ. He has trained very well and showed against the Barbarians and in his short time on the field in the 1st Test that he is ready to make the step to international rugby. To have two 21-year-old centres is exciting and we are looking forward to seeing this combination in action.
“Owen has had a fantastic season and I am sure he will make a significant impact from the bench. However, Toby has waited patiently for his opportunity and the time is right to allow him the chance to demonstrate his experience and skills in what will be a very tough challenge.
“It’s a shame for Mike Brown who worked hard to get that Test start but Ben Foden naturally reverts to full back and we return to the wing partnership of David Strettle and Chris Ashton that served us well in the RBS 6 Nations.”
England team to face South Africa
15 Ben Foden (Northampton Saints)
14 Chris Ashton (Northampton Saints)
13 Jonathan Joseph (London Irish)
12 Manusamoa Tuilagi (Leicester Tigers)
11 David Strettle (Saracens)
10 Toby Flood (Leicester Tigers)
9 Ben Youngs (Leicester Tigers)
1 Joe Marler (Harlequins)
2 Dylan Hartley (Northampton Saints)
3 Dan Cole (Leicester Tigers)
4 Mouritz Botha (Saracens)
5 Geoff Parling (Leicester Tigers)
6 Tom Johnson (Exeter Chiefs)
7 Chris Robshaw (capt, Harlequins)
8 Ben Morgan (Scarlets)
16 Lee Mears (Bath Rugby)
17 Alex Corbisiero (London Irish)
18 Tom Palmer (Stade Francais)
19 Phil Dowson (Northampton Saints)
20 Lee Dickson (Northampton Saints)
21 Owen Farrell (Saracens)
22 Alex Goode (Saracens)