But England eclipsed it with a mammoth 250-3 on the same Taunton wicket.
Bates, on the other hand, just kept on biffing - 16 fours and three sixes all told - and had she not been deprived of the strike in the final over, she would surely have overhauled Meg Lanning's T20-highest innings of 126.
Bates' 124* is also the highest individual score by a New Zealand player in T20I format (Men/Women) surpassing Brendon McCullum's 123 against Bangladesh in the 2012 WT20.
Van Niekerk's half-century could not prevent her side from suffering the heaviest defeat in Women's Twenty20 internationals - topping the 115-run loss South Africa had inflicted on Netherlands in Potchefstroom in 2010 - on a day the Proteas will want to forget.
Pace bowler Marizanne Kapp bowled only two overs before leaving the field with heart palpitations.
"If you're not relaxed going in to bowl when you've got 250 on the board then you are never going to be, but we were really keen not to rest on our laurels and put in a professional bowling and fielding performance, which I think in the main we did".
"Thanks to England, she's seen the doctor and hopefully she's OK".
After setting up such a huge total, England's victory was evident but some fight back was also expected from South Africa Women, which did not come. "This was close to a ideal performance".
South Africa had a long way to go to threaten England's target but despite a good knock from captain Dane van Niekerk they never got close. "We spoke between games about what we wanted to do, but did the complete opposite".
Wyatt fell for 57 but Beaumont raced along to bring up her three figures in just 47 balls, second only to Deandra Dottin's record of 39 balls.
2639 - Suzie Bates became the leading run-getter in the T20I cricket (Men/Women) history with her century.