Imran Tahir ripped through West Indies, becoming the first South African to take seven wickets in a one-day international in a resounding win.
The leg-spinner finished with figures of 7-45 to lead his team to a 139-run victory in Basseterre in the tri-series on Wednesday.
Tahir did the bulk of the damage with the ball as South Africa cruised to a bonus-point win at Warner Park.
Hashim Amla (110) had set his side up after they were put in to bat, guiding them to 343-4 from their 50 overs.
Faf Du Plessis (73 not out) and Quinton De Kock (71) were also strong contributors in the bonus-point win.
Tahir was almost unplayable as Johnson Charles (49) top-scored for the Windies as they were bowled out for 204.
West Indies won the toss and put South Africa in, a decision captain Jason Holder was soon lamenting as Amla's masterful century provided the foundation for the tourists' innings.
Fellow opener De Kock also batted beautifully, with South Africa piling up a giant 182-run partnership for the first wicket.
Amla hit 13 boundaries before he was caught by spinner Sunil Narine off the bowling of Kieron Pollard.
De Kock was bowled by Jerome Taylor for 71 but the runs kept flowing for South Africa, with Chris Morris making a rapid 40, but it was Du Plessis who forced his side on beyond 300.
With Taylor particularly leaky - his eight overs went for 72 runs - Du Plessis caught fire with a terrific unbeaten 73, clearing the ropes twice.
There were also a pair of sixes for AB De Villiers, who made a quick 27 before Pollard struck with his second wicket.
Narine was the only bowler to provide any control for West Indies, his 10 overs costing just 46, but South Africa's total of 343-4 was always likely to be too big for the hosts to chase.
That proved to be the case despite a fast start as Charles and Andre Fletcher (21) reached 69 when Tahir removed the latter in the ninth over.
The wickets fell at regular intervals from that point on with Marlon Samuels (24) the second highest scorer for the Windies.
Tahir was decisive, taking the final six wickets of the innings in a huge win for South Africa.