Transition food gradually to give your cat's tummy & taste buds time to adjust.
Start with a small scoop in the same bowl with the old food, keeping the foods separate.
Slowly increase the proportion of new food to 50% of the bowl.
Begin mixing the foods together, gradually increasing the proportion to 100%.
Listen to your cat and pace based on how they are adjusting. Don't fret - it can take up to a month for some cats!