The project will be carried out through CT Properties Ltd, the firm said in a stock exchange filing.
Edmonton Ltd, a unit of the Keppel Land Ltd, will take a 60 percent equity stake and debt in the company.
The apartment is earmarked to be built on a 1.25 acre block in Colombo's George R de Silva Mawatha.
CT Holdings said Keppel had entered into a conditional share purchase agreement which includes gaining regulatory approvals before buying its stake.
Keppel Land is one of the largest property companies in Singapore.