The ship will be built by German shipbuilder Meyer Werft on substantially the same terms as the first Sunshine ship.
“This confirms our continued confidence in the success of this new generation of ships and our strong conviction about the Royal Caribbean International brand,” said Richard Fain, chairman and chief executive of Royal Caribbean Cruises.
Sunshine-class ships are the second largest in the Royal Caribbean fleet, behind Oasis class vessels.
Royal Caribbean has its first Sunshine class ship scheduled for delivery in the fall of 2014.
Royal Caribbean is a global cruise vacation company that also operates Royal Caribbean International, Celebrity Cruises, Azamara Club Cruises, Pullmantur, CDF Croisieres de France, as well as TUI Cruises through a 50 per cent joint venture with TUI AG.
The company owns a combined total of 40 ships and has three ships on order.
It also offers unique land-tour vacations in Alaska, Asia, Australia/New Zealand, Canada, Dubai, Europe and South America.