This follows a memorandum of agreement signed in July 2018.
Each ship will have double-occupancy capacity for approximately 4,300 passengers.
The next-generation design features a dual-fuel system, primarily powered by LNG.
Step up in size
The ships will outsize the current Royal class, at 143,700gt with 3,660 lower berths. The latest of those ships, Sky Princess, is scheduled for delivery this October.
'Princess Cruises continues to grow globally—adding new ships to our fleet built by our longtime, trusted ship building partner, Fincantieri, which brings decades of expertise to these next-generation cruise ships,' Princess president Jan Swartz said.
She added the newbuilds will have the line's MedallionClass platform, powered by the OceanMedallion wearable device.
Fincantieri CEO Giuseppe Bono said the order represents a 'record-breaking proposal, not only in terms of size,' and underscores the trust the market holds in the shipbuilder.
Fincantieri, he noted, has built or is building 21 ships for Princess.