Fortuin and Rabada took two wickets each to restrict Sri Lanka to 120-8 before De Kock (59) and Hendricks (56) helped South Africa romp home in 14.4 overs.
Follow live score and commentary from Day 3 of the third T20I between Pakistan and South Africa.
India vs South Africa 3rd T20I: Proteas captain Quinton de Kock says team stuck to plans, kept pressure on hosts to clinch victory
The margin of victory was big but South African captain Quinton de Kock was equally impressed with the manner in which his team fought back to win the third T20 International against India and level the series.
India vs South Africa 3rd T20I: Quinton de Kock, Beuran Hendricks star in Proteas' series-levelling win against Virat Kohli and Co
Quinton de Kock's unbeaten 79 led South Africa to a nine-wicket win over India in Bengaluru as they drew the three-match T20I series 1-1
India vs South Africa: Captain Virat Kohli says new players will be tried to see who stands up under pressure
Kolhi, who smashed an unbeaten 72 to guide India to a seven-wicket win over South Africa in the second T20 International on Wednesday, credited his bowlers for restricting the visitors to a modest 149 for five.
India A vs South Africa A: Manish Pandey, Shivam Dube shine as hosts win third unofficial ODI, take unassailable 3-0 lead
Dube smashed an unbeaten 45 off 28 balls while Pandey plundered 81 off 59 balls as India A overcame a poor start to win the rain affected match rather comfortably in the end. Chasing 208 in 30 overs, India A reached the target in 27.5 overs.