The two new ships will be sister ships to the two confirmed last year -- Viking Star and an as yet unnamed sibling. They will be built at the Italian Fincantieri shipyard.
Deliveries of the 48,000-ton, 928-passenger vessels are scheduled for mid-2016 and early 2017, according to a news release from Fincantieri. Viking has conditional orders and options on two further ships.
Fincantieri and Viking added that they are "discussing additional high-profile joint projects in other cruise segments" as part of their ongoing partnership.
Torstein Hagen, Chairman of Viking Cruises, said: "The interest in and popularity of our current ocean itineraries has been incredible, and they are selling at an unprecedented rate."
Viking said it would likely comment further on the order next week.
Giuseppe Bono, CEO of Fincantieri, said: "This new order strengthens our partnership with Viking, a group that is displaying remarkable dynamism and ability to achieve important market goals."
In October, Viking started selling winter 2015 cruises on Viking Star as well as select 2016 cruises in the U.S. only.
The ocean ship order follows the company's extraordinary fleet expansion in the river cruise sector, with 10 new river ships christened this year, and 14 more river ships planned for launch in 2014 and 2015.
--by Adam Coulter, U.K. Editor