This will be the third time Gatland leads the Lions as head coach‚ having successfully guided the team to a 2-1 series win over Australia in 2013 and an epic 1-1 drawn series against the All Blacks in 2017.
The former hooker was also assistant coach to Ian McGeechan when the Lions last toured SA in 2009.
Should Gatland’s Lions avoid defeat‚ he would create history by becoming the first person to lead tours to Australia‚ New Zealand and South Africa and remain unbeaten.
"I’m hugely honoured and delighted to lead the Lions again‚" said Gatland.
"It is exciting and a great challenge to coach the best players from the four Home Nations.
“The Lions rightly have a truly special place in the game and I jumped at the chance to be involved again when I was approached about the role.
"South Africa is a special place to play rugby.
"They have some of the most iconic stadiums in the world which will be packed full of passionate fans‚ and the Springboks have shown in recent times that they are back to being one of the dominant forces in the game.
"Having toured there in 2009 I know the scale of the task ahead of us – playing in South Africa presents a number of unique challenges such as playing at altitude‚ while the Boks will always be physical‚ aggressive and highly motivated.
"History tells you it’s a tough place to tour‚ but I am 100 per cent confident that we can go there and win – I would not be here if I thought differently.
"I’m delighted to now have everything in place to begin full-time in August 2020 as that gives me the best possible chance to plan for South Africa‚ but for the time being my focus is entirely on the Rugby World Cup and delivering a successful campaign for Wales."
Following this year’s Grand Slam victory Wales remain on a record-breaking 14-match winning run.
Having also coached Ireland from 1998 to 2001‚ Gatland is unparalleled in terms of experience at international level with 158 Tests to his name so far.
Domestically‚ Gatland has also coached Connacht and Wasps – winning three English Premiership titles and a Heineken Cup during his time in London – before a stint with hometown side Waikato in New Zealand where he claimed the Air New Zealand Cup.