The islet called Uchchimunai off Kalapitiya north of Sri Lanka's capital Colombo is among several state-owned that have been offered to foreign investors.
The firm is expected to build a resort with hotels, water villas and a golf course on the islet.
Sri Lanka has seen a tourism boom with the end of a 30-year war in 2009 with 855,000 tourist coming in 2011.
This year arrivals are expected to top one million.Corrected up front payment Rs,1,070mn