Although cats are natural predators of rabbits, this combination is remarkably successful, with introductions being more straightforward than those with dogs. One factor that facilitates cat/rabbit friendship is the complementary body language of the two species. A dominant rabbit may push his head under the cat's chin, "presenting" in order to demand a lick. With cats, it is the dominant one doing the grooming so, when a cat grooms a rabbit, each animal happily believes he is the boss! The best strategy of you want a house rabbit and a cat to live alongside one another is to choose a large bunny. You need to be cautious of your rabbit is a dwarf breed and the cat is a hunter. You will probably find that the rabbit prefers not to use the same litter box as the cat.
The process of introducing cats and rabbits is similar to that outlined for rabbits and dogs. You should make the first introductions with one of the animals in a cage. As with dogs, the cat should be rewarded for displaying calm behavior around the bunny, and she should learn to associate the presence of the rabbit with pleasant things. For example, you could feed your cat next to the rabbit. it also helps if the cat is familiar with the smell of the rabbit. Transfer the scent of the rabbit to the cat by stroking both animals with a cloth, in turn.
Once the cat and rabbit are relaxed, you can start to let them out together. Close supervision will be essential at first, but it should take long for the two to settle down and become good friends.
There are many cases of house rabbits and cats that have developed such a strong bond that they groom each other, and sleep and play together, although this shouldn't be allowed until your cat has learned to keep her claws retracted.
When you are sure that cats and rabbit are best buddies. you can leave them together all the time. However, this could take time, and, until then, separate them when you are not around to supervise.