The ship class will debut in summer 2027 with the launch of Oceania Sonata before the second vessel – Oceania Arietta – arrives two years later.
Each Sonata Class ship will carry approximately 1,390 passengers and measure approximately 86,000 tons.
Oceania Cruises’ chief luxury officer Jason Montague made the announcement at Oceania Allura’s delivery ceremony in Genoa, Italy.
Montague said: “I am delighted to confirm we will be adding two more Sonata Class vessels to our fleet. We are proud to continue our legacy of innovation alongside Fincantieri, our shipbuilding partner for close to 20 years.
"These four Sonata Class ships will herald the next stage in the evolution of the Oceania Cruises brand of exceptional small-ship luxury experiences."
Meanwhile, Montague called the 1,200-passenger Oceania Allura the line’s "most innovative and luxurious ship to date".
Montague added: "[Allura] represents our bold vision for an entirely new generation of luxury travel experiences."
"As always, at the heart of this beautiful ship is an extraordinary crew dedicated to providing exceptional cuisine, personalised, intuitive service and immersive enrichment opportunities for our guests."
Allura features the Creperie, a new venue for the Norwegian Cruise Line Holdings brand; French signature restaurant Jacques; and pan-Asian speciality eatery Red Ginger.
The Grand Dining Room has more than 270 new recipes curated by Oceania’s culinary team.