This nearly square breed should be powerful and active — a combination of strength, endurance and alertness. It should appear to be 60 percent mastiff and 40 percent bulldog. Its gait is smooth and powerful, but its angulation is moderate. Its coat is short and dense, and its expression keen and alert. These attributes allowed the bullmastiff to both overtake and over-power intruders.

The Bullmastiff is innately good-natured, calm, easygoing and surprisingly gentle. It is a well-mannered house pet, but it needs sufficient room to stretch out. This is an extremely loyal breed, and though not excessively demonstrative, it is devoted to its family and good with children.