Opener Natalie Dodd shone with a tenacious 52 at the top of the innings as the visiting side stumbled to 208 for eight.
But South Africa batted poorly, slumping to be all out for 113, handing the White Ferns an unassailable 4-1 lead in the seven-match series.
Nothing early in the match suggested such a large winning margin.
Proteas Ayabonga Khaka and Marizanne Kapp have snatched the lion’s share of wickets between them in the series and the combination held court for the first 11 overs, reducing the White Ferns to 22 to three.
Dodd and the in-form Amy Satterthwaite stitched together a recovery, their 84-run stand for the fourth wicket the highest of the White Ferns’ innings.
Satterthwaite reached 42 from 47 balls when disaster struck.
She was run out in the 27th over after Dodd smashed a straight drive only for bowler Sune Luus to tip it on the non-striker’s wickets with Satterthwaite out of her ground.
Katie Perkins (34) and Sam Curtis (42) helped the White Ferns get past 200.
Mignon du Preez top-scored for the Proteas with 62 but only Luus with 27 was able to offer much resistance.
White Ferns captain Suzie Bates took three for 17 from five overs and spinner Erin Bermingham took three for 28 as the home side capitulated.
The sixth ODI tomorrow will also now take place at Paarl’s Boland Park, having been moved from Coetzeburg Oval.
