Spirit of the Moselle, Spirit of the Main, Spirit of the Elbe and Spirit of the Rhone will operate across each river, with the first due to come into service in May 2023 with the others following each year thereafter.
The vessels will join the brand’s two existing river ships and be operated as part of the wider cruise business under chief executive Nigel Blanks.
"We are so excited about the opportunity to expand our fleet of river ships to keep up with the ever-growing demand for luxury boutique river cruising," Blanks said.
"It builds on the success of Spirit of the Rhine and Spirit of the Danube which were launched this weekend and on our award-winning ocean cruise offer.
"These new ships will enable us to offer an even greater range of boutique experiences to guests looking to travel on the waterways throughout Europe."
