Corn snakes' preferred diet consists primarily of small mammals, particularly rodents. In the wild, they commonly feed on mice, rats, and other small rodents suitable for their size. Studies on the feeding habits of corn snakes suggest that they play a crucial role in controlling rodent populations.

Corn snakes are opportunistic feeders, meaning they will eat a variety of prey when available. Apart from rodents, they may consume unguarded bird eggs, birds, reptiles, amphibians, and invertebrates.