Condor's converting six cabins on the Commodore Clipper to be pet-friendly.
It follows the popularity of people travelling with their dogs on the Islander.
The ferry firm's conventional ferry came into service in October 2023. In a first for the company, it included six cabins that will allow dogs.
Previously, all pets travelling with their owners had to remain in the passenger's vehicle throughout the journey.
Condor boss John Napton says there has been lots of positive feedback about the pet-friendly cabins, so they will add six to the second vessel in time for the summer season.
"We are seeing more pet travel in recent years and the reaction from passengers travelling on Islander has been overwhelmingly positive, so we have listened and are now extending this to Clipper."
The ferry firm says it carried 16,600 pets on its UK and inter-island routes in 2022, which was almost a third more than before the Covid pandemic.
The six cabins on Clipper will each feature hard, laminate flooring and an outside deck will be accessible for exercise.
Pets can still be kept in a vehicle or an appropriate pet carrier on the car deck on the Clipper, Islander, Liberation and Condor Voyager.