No. Grapes and raisins are on the ASPCA’s list of foods to keep away from pets. Kidney damage is best documented in dogs, but the risk to cats is not ruled out.

Can Cats Eat Grapes? No

If your cat ate grapes

Call your vet or a poison line for advice.
Watch for vomiting, lethargy or drinking and urinating less.

Call your vet or a 24/7 animal poison line now: ASPCA Animal Poison Control (888) 426-4435 · Pet Poison Helpline (855) 764-7661

Why

Few cats eat grapes, but raisins in baked goods and trail mix are easy to overlook. Because no safe amount is known, treat any amount as a reason to call your vet.

Sources

ASPCA — People Foods to Avoid Feeding Your Pets
Pet Poison Helpline — Grapes and Raisins

General information checked against published veterinary sources. Every cat is different — ask your vet before changing its diet, and call them if it seems unwell.