England women added the Twenty20 series to their One-Day success over South Africa by winning the deciding match in Johannesburg by four wickets.
Sarah Taylor hit 60 off 40 balls – her third successive fifty – and, despite losing three wickets in eight balls, England chased 132 with 27 balls left.
South Africa were reduced to 6-3 in the second over as Anya Shrubsole struck twice in two balls.
But Lizelle Lee’s career-best 69 not out helped them post 131-4.
England’s 2-1 series win, which matched the ODI series result, was their last competitive action before their opening World Twenty20 match against Bangladesh on 17 March.