Chasing 158, the hosts held their nerve to reach the target in the final over, finishing on 158/4. Chloe Tryon applied the finishing touch in emphatic fashion, launching a six off the opening delivery of the 20th over to seal the result, ending unbeaten on 18.
Captain Laura Wolvaardt led from the front at the top of the order, striking a composed 51 from 39 balls after returning to her preferred opening role. She found strong support in Annerie Dercksen, who produced an assured unbeaten 44 off 34 deliveries to guide the chase home.
Earlier, South Africa's bowlers and fielders combined effectively to limit India to 157/7, despite the visitors racing to 46 without loss inside the opening five overs. Disciplined bowling and sharp work in the field helped rein things in after the early momentum.
For India, Shafali Verma made a brisk 34 off 20, while Jemimah Rodrigues contributed 36 from 29. Captain Harmanpreet Kaur anchored the innings with an unbeaten 47 off 33 balls.
With the ball, Ayabonga Khaka was outstanding, claiming 3/16 from her four overs, while Tumi Sekhukhune chipped in with 2/27.
The second match of the five-game series will take place at the same venue on Sunday.
Tebogo Macheke has earned her first call-up to the Proteas Women's squad for the upcoming five-match T20I series against India, with the national side also making changes to the coaching staff.
Proteas Women's seamer Ayabonga Khaka has jumped to 12th in the latest ICC world bowling ranking after an outstanding ODI series in New Zealand where she was the leading wicket-taker.
New Zealand clinched a 2-1 series victory over South Africa with a 66-run win in the final women's ODI in Wellington on Saturday, bringing the tour to a disappointing close for the visitors.
Amelia Kerr put on a show as she guided New Zealand Women to a record run chase of 346 for a narrow two-wicket win in the second ODI in Wellington on Wednesday.
