The hosts bounced back from their shock 52-run loss to Australia’s National Performance Squad (NPS).
Bowlers Ben Cutting and Kane Richardson returned figures of 4/27 and 3/13 to restrict South Africa to a modest 160 with four balls remaining, after winning the toss and putting the visitors in to bat first.
Dominic Hendricks (20) and Heino Kuhn shared the only 50 partnership of the innings before the latter was dismissed by Cutting for 30 in the 11th over.
The bowler struck a second time in the same over when Rilee Rossouw was trapped without scoring.
The South Africans struggled to form lasting partnerships thanks to the rampant attack.
They lost Vaughn van Jaarsveld (5) and skipper Justin Ontong (2), before Farhaan Behardien and Mangaliso Mosehle (20) shared a 36-run partnership for the sixth wicket that gave some stability.
Aaron Phangiso (15) once again showed his ability with the bat, hanging on stubbornly for 40 balls before Cutting dismissed him.
Beuran Hendricks and Mthokozisi Shezi also contributed 32 vital runs for the 10th wicket and, along with the added 15 runs conceded in extras, gave South Africa a respectable total.
Cameron White scored 68 from 113 balls in reply, including nine fours to set his side on the road to victory.
Phangiso took the wickets of Cutting (0) and Alex Doolan (19) to slow down the scoring rate, but in the end, Callum Ferguson’s (35) unbeaten 39-run, fifth-wicket partnership with Tom Cooper (14*) saw Australia A win comfortably with 28 balls to spare.
South Africa now lie at the bottom of the points table ahead of their match against India A on Saturday.