A quickfire 39 off 27 balls from opener Aaron Finch set the platform for the victory as Australia reached 129 for four with five overs to spare in reply to South Africa's 128 for seven off 20 overs.
The home side struggled on a slow and difficult pitch and only opener Quinton de Kock, who scored 41, emerged with any plaudits as wickets fell around him.
Australia fast bowler Mitchell Starc produced an impressive variation of pace to take two wickets and, as importantly, concede just 16 runs in his four overs.
Finch and Cameron White did not seem to have the same difficulty with the wicket, amassing a quick 43 runs in the first five overs as Australia switched their dominance from ball to bat.
Shane Watson pitched in with 35 off 28 balls to ease the touring side to victory.
"It puts us in a good way for the World T20," he told reporters.
On Wednesday, Australia produced an exhibition of ferocious batting to edge South Africa in the last over of a match reduced by rain to just seven overs each in Durban.
- Sports & Recreation
- Aaron Finch
- South Africa
- Mitchell Starc