Shepherd and Joseph gave West Indies the third-highest score at the Wanderers and the highest total without an individual fifty since Australia’s 221 for 5 against England in 2007.
They were able to defend it in challenging conditions, with plenty of dew greasing up the ball, and against a determined South African line-up.
Reeza Hendricks notched notched up a career-best 83 and put on 80 with Riley Rossouw for the second wicket but the required run-rate ballooned on South Africa and their batting line-up appeared a little light.
The result means West Indies have now won a second successive T20I series win in South Africa, eight years after taking the trophy in 2015. Sheldon Cottrell and Jason Holder are the only members of the current squad who played in that series.