Sudharsan, 21, has only played eight first-class matches for Tamil Nadu, scoring 598 runs at an average of 42.71, including two hundreds and a half-century, with a highest score of 179.
Sudharsan has also been a mainstay for previous champions Gujarat Titans in the Indian Premier League during the last few seasons, scoring 507 runs in 13 matches at an average of 46.09 and a strike rate of 137.03, with a best score of 96.
He made his India ‘A’ debut a few months ago in the Emerging Asia Cup, when he smashed a ton.
Speaking on Sudharsan’s signing, Surrey head coach Alec Stewart said, “With the busy schedule of international and domestic cricket around the world, I’m pleased to add Sai Sudharsan to our available squad of players.
“Sai has come highly recommended to me by people I highly respect, including a couple of the greats of the Indian game, who have seen and worked closely with him.
“Sai will add to the batting options for the final three games of the season, and we look forward to welcoming him to the dressing room,” Stewart said in a club statement.
Sudharsan will be available for Surrey’s September 3 home game against Warwickshire, September 19 home game against Northamptonshire, and September 26 away game against Hampshire.
After Kemar Roach of the West Indies, he will be the club’s second overseas acquisition for the time.
Surrey presently leads the Championship’s Division One points table by 17 points over second-placed Essex.
(With inputs from PTI)