Along with two foreign partners, DSME E&R will build the floating LNG production and storage unit with an annual output capacity of 3 million tons of gas.
Details of the project will be revealed later, it said.
The 3 million tons of gas are equivalent to 15 per cent of the country's consumption of the fuel, it added.
The partners include Hoegh LNG and Petromin PNG Holdings, Daewoo Shipbuilding said.
Shares of Daewoo Shipbuilding were trading at 34,950 won on the Seoul bourse as of 10:45 a.m., up 0.58 per cent.