The new flights will go on sale on March 24 and will be operated by a Boeing 787-9.
The service will begin flying in winter 2018 with the first flight departing on October 28, 2018. With two flights per day, Virgin Atlantic expects to carry more than 300,000 customers annually.
flight will depart Heathrow at 16.45 and land into Johannesburg at 05.40 local time. The service will be the first Heathrow flight to land each morning.
The return flight will leave Johannesburg at 22.20 landing back into Heathrow at 07.30.
The route has been timed to enable customers to easily connect onto flights with Virgin Atlantic and Delta.
Shai Weiss, chief commercial officer at Virgin Atlantic, said: “Virgin Atlantic has been proud to serve South Africa for over 20 years. Johannesburg is one of the most popular destinations on our network so we’re delighted to add a second daily service to create even more travel opportunities for our customers.”
The new South African flights will offer 36 Economy Delight seats on each service - with priority check-in and boarding, free seat selection and 34inch extra legroom seats.