An unbeaten knock from Ash Gardner has guided Australia to a final over victory against South Africa in the third T20 international at Hobart's Bellerive Oval.

The win saw Australia clinch the three-match T20 series 2-1.

With Australia in pursuit 7-162, Gardner played a crucial hand in the hosts chasing down South Africa's total with four balls to spare.

Joining opener Beth Mooney with the home side poised at 4-104 and requiring a further 58 from 40 balls for victory, Gardner delivered an unbeaten 26 from just 17 deliveries, ensuring her side didn't lose momentum towards the back end of the chase.

Striking at 152.94, she faced just four dot balls and struck two boundaries and a six in her short yet effective cameo innings.

The most crucial of them came from the last ball of the 19th over after she dispatched South African seamer Marizanne Kapp past long off for a boundary, leaving two runs required from the final over of the match.

Opener Beth Mooney (82 from 55) anchored the Australian innings, the left-hander awarded Payer of the Match honours.

Earlier in the contest Gardner was expensive with the ball, conceding 33 runs from her four overs.

She picked up her only wicket in the opening over of the match, dismissing dangerous South African opener Tazmin Brits (0 from 4) who was caught comfortably at long on by Grace Harris.

Allrounder Marizanne Kapp (75 from 48) was the pick of the South African batters.

Gardner and her Australian teammates next face South Africa in the first of three one-day internationals at the Adelaide Oval on Saturday.