Uniworld has taken eight of its U by Uniworld sailings off general sale and will offer places to agents of all ages.
The sailings along the Seine, Danube and Rhine will not be on direct sale to the public and will be removed from the U by Uniworld website.
The luxury river cruise line said the decision was made after the success of its “Sneak Peek” cruise on The B last month, with agents expressing interest in experiencing the brand first-hand.
A total of 20 rooms per cruise will be available at an rate of 60% off the published fare on select itineraries on The A and The B in April, May, August and October 2018.
Agents will also be able to book their clients of any age on to the cruises.
Uniworld Boutique River Cruise Collection launched its youth river cruise brand earlier this year for 21-45-year-olds.
The vessels have a capacity of 120 passengers and feature a sleek interior design with open communal spaces and rooftop lounges.
Other features include a gym, rooftop yoga classes as well as a large fleet of bicycles for passengers to use.
Ellen Bettridge, president and chief executive of Uniworld, said: “We want to ensure we are providing travel agents the best opportunities to not only experience this history-making river cruise for themselves but to also best meet the needs of this diverse millennial generation.”