No Roombas or any other Robot Vacuum models state any specific weight limit. But I tested my Roomba and it can easily carry 5 liters (11 lbs.). This means your Roomba will also easily be able to carry your cat around. If you put weight on your Roomba, let's say your cat, for example, you will notice that it will deplete its battery faster and it will not go around your house as fast. Stuck hairs and dirt in the wheels will also be more troublesome to deal with on top of the added weight.