Royal Caribbean has placed an order for a third ship in the 5,400-passenger Oasis class from the STX France shipyard.
The ship will be the same size as the Oasis of the Seas and Allure of the Seas, and is intended for delivery in 2016.
Royal Caribbean had been negotiating with STX Finland.
However, the deal fell through after a failure to agree support from the Finnish government.
Royal Caribbean has also signed a one-year option to build a fourth Oasis-class ship from STX France.