South Africa made 6-222 after selecting to bat first with shock choice Heinrich Klaasen top-scoring with 66 from 33 at his dwelling floor and Temba Bavuma making 49 from 24.
England’s key partnership was Morgan’s stand with Ben Stokes, which reaped 61 runs from 27 balls.
The guests wanted 53 from the final 4 overs however Morgan hit two sixes within the 17th over, Stokes did the identical within the subsequent over, and Morgan did it once more within the 19th.
Stokes, who scored 22 from 12, was caught on the boundary firstly of the penultimate over and England nonetheless had work to do.
England in the end solely wanted one run off the final six balls with Moeen Ali sending a 4 down the bottom for the victory.
England’s 5-226 was their second-highest whole batting second in T20s and the fifth-highest ever for a staff batting second.
Morgan’s 50 got here off 21 balls, equalling his personal document set final 12 months in New Zealand for the quickest T20 half-century by an England participant.
The victory gave England a successful finish to the tour in Centurion, the place it began with the primary Check in December.
England got here from behind in each one of many three series, preventing again to win the Check series 3-1, to draw the ODI series 1-1, and to win the T20 series 2-1.
The success can be particularly welcome for England with the T20 World Cup in Australia in October and November. England misplaced to the ultimate of the final T20 World Cup to the West Indies in 2016.