Bouchier, who's played for the Melbourne Stars in the Women's BBL, hit 126 on her Test debut, sharing in a 174-run partnership with Sciver-Brunt in Bloemfontein on Sunday.
Sciver-Brunt also starred with the bat, hitting the fastest women's Test hundred from 96 balls, finishing with a blistering 128 before being run out by Nonkululeko Mlaba.
The Proteas' spinner proved to be the pick of the bowlers and helped South Africa get a grip on the game in the evening session as she took three wickets after tea to spark an England collapse before the tourists declared at nine wickets down.
South Africa openers Laura Wolvaardt and Anneke Bosch then successfully navigated the final six overs of the day to close on 17 without loss.
After winning the toss, England opted to bat first and brought up their 50 without loss inside 11 overs.
South Africa soon found the breakthrough in the following over when Tammy Beaumont was caught by Sune Luus off Ayanda Hlubi for 21, but Bouchier continued to impress alongside skipper Heather Knight for England to reach lunch on 1-103.
The hosts struck again in the first over of the afternoon session when Tumi Sekhukhune dismissed Knight lbw for 20.
All-rounder Sciver-Brunt brought up her half-century from just 46 balls, while Bouchier went to three figures in style after smashing a brilliant boundary.
Bouchier eventually went for 126, edging to Luus in the slips off Mlaba, who quickly picked up her second wicket, dismissing Danni Wyatt-Hodge for 12.
Sciver-Brunt's brilliant innings ended in unfortunate circumstances after Amy Jones (39) cracked a shot down the wicket, only for bowler Mlaba to stick out a hand and deflect the ball onto the stumps at the non-striker's end, leaving the all-rounder stranded out of her ground.
Mlaba's efforts sparked a flurry of dismissals as she bowled Charlie Dean, who got in a tangle in the crease and the ball skidded onto the stumps.
The bowler shortly earned her fourth after Jones chipped to mid-off, allowing Marizanne Kapp to make an easy catch for the England wicketkeeper to fall for 39.
Kapp earned her first scalp of the day after bowling debutant Ryana MacDonald-Gay while Hlubi bowled Sophie Ecclestone four balls later before Knight declared.
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