Duminy will replace Ricky Ponting as the former Australian captain was only signed as cover for Graeme Smith for June and July.
London: English county Surrey announced on Tuesday their third major overseas signing this year when the London-based club revealed that South Africa's JP Duminy would be joining them in August.
Surrey, whose headquarters are at The Oval -- England's oldest Test ground -- started 2013 by announcing South Africa Test captain Graeme Smith, who has since suffered a season-ending injury, as their new skipper.
Australia great Ricky Ponting is currently filling in as Surrey's overseas star.
Duminy, 29, will replace Ponting after South Africa's tour of Sri Lanka and is available for six County Championship matches as well as the end of the domestic 40-over and Twenty20 competitions.
"I am really chuffed to have signed with a great club like Surrey," said top-order batsman and occasional spinner Duminy, currently with the Proteas squad competing in the one-day Champions Trophy tournament.
"I love the UK and I really look forward to working with Chris Adams and the rest of the team."
Surrey team director Adams added: "I am delighted that JP Duminy has agreed to join Surrey for what will no doubt be an exciting and important period of our season. We are happy to be welcoming him to the club and look forward to him making a big contribution during his time here."