Corn on the cob — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
Dangerous for dogs: the cob is a classic cause of intestinal blockage and can be fatal. Kernels off the cob are fine.
Short answer
The kernels are safe, but the cob is dangerous. Like with dogs, the cob can cause a life-threatening intestinal blockage in cats. If your cat nibbled only kernels, there is no worry. If your cat swallowed any part of the cob, watch closely for vomiting, lethargy, or straining to defecate over the next 24–48 hours. Call your vet or the ASPCA Poison Control line at 888-426-4435 right away if you suspect cob ingestion.