Hooker Bismarck du Plessis scored twice from rolling mauls in a much-improved second half showing after the Springboks took a narrow 18-13 lead into the break.
There were also tries for Bryan Habana and Bakkies Botha, both returning after a glory-filled season with Toulon in France, and late efforts by Johan Goosen and Willie le Roux.
The home side, who play two tests against Wales followed by one against Scotland on the next three Saturdays of this month, were slow to start and went behind after four minutes.
Former South Africa lock Alistair Hargreaves, now playing in England with Saracens, twisted his way over from close range for the first try.
Habana grabbed the first touchdown for the Springboks in the 17th minute and then set up the second for Botha.
The second half turned into a relatively easy exercise for the Springboks against a team mostly made up of players from clubs in England and France.
"Our attitude was there but perhaps not the legs after a long season," World XV captain Matt Giteau told reporters.
The home pack showed their power as Du Plessis scored his double and there was also some flair shown towards the end for the last two tries.
"The first 30 minutes had some great intensity and it's a good way to go into the three tests we have coming up," said South Africa's stand-in captain Victor Matfield.
"Next week we have a serious test match and there were one or two mistakes today that we need to work hard on eliminating."
No test caps were awarded for Saturday's match.
