The extensions comprise a stay in a centrally located hotel, with guests free to explore the city at their own pace, but Riviera has also partnered with online travel platform holibob so customers can also book recommended tours and experiences.
The extensions, spanning six countries, are in Amsterdam, Basel, Cologne, Frankfurt, Lyon, Marseille, Munich, Paris, Porto and Vienna.
As part of the booking price, all city breaks include return flights with a choice of UK regional airports, transfers from the ship to the hotel and hotel to the airport and a daily breakfast.
The move comes after Riviera reported an increase in the number of guests requesting to stay on independently after their river cruise.
Riviera has also added a new a 10-night Lyon, Provencal Rhone and the Camargue river cruise to operate from April to October.
The cruise comprises 14 tours and visits, including guided tours of Cluny Abbey, Lyon, Arles, Avignon, Beaune and Hospices de Beaune; wine tastings in Macon and Chateauneuf-du-Pape and guided excursions to the Camargue and Ornithological Park of Pont de Gau.
Prices start from £2,249pp and includes flights and transfers, onboard meals, welcome cocktails and dinner, onboard tea and coffee and a cruise director. The city stay extension in Lyon is available to guests who travel on the cruise.
Katja Hildebrandt, head of product, river and ocean cruise at Riviera Travel, said an increasing number of the brand’s guests are looking to spend additional time away after their river cruise.
"From relaxing with a cafe au lait and croissant in a Paris cafe to experiencing the architectural grandeur of Cologne, or having time to visit the many museums in Amsterdam, our city stays allow guests to explore even more, safe in the knowledge we will take care of all accommodation and travel arrangements," she added.
"Meanwhile our new Lyon, Provencal Rhone and the Camargue itinerary has a stunning schedule we’re confident guests will love. It will provide the very best tours and visits to a wonderful part of France, and offer the perfect combination of discovery and relaxation."
