Celeriac — Food safety facts
Safe to share · Cats · full breakdown on the linked food page
Peeled and cooked, in small pieces.
The full verdict, portion guidance and serving notes are collected on the Celeriac food facts page.
Short answer
Yes, celeriac or celery root can be used as a filler in some commercial cat foods or treats. It's safe for cats in small, cooked amounts, so finding it in an ingredient list isn't a cause for alarm. Just feed it as part of a balanced diet and watch for any digestive upset. If your cat has an unusual reaction, contact your regular vet.