Cats, dogs and bears all belong to the Carnivora clade of mammals, but they are not the only ones belonging to this clade.
For instance, cats are more closely related to mongoose and hyenas than to dogs or bears, who in turn are more closely related to raccoons, weasels, and walruses.
Their common ancestors likely displayed various adaptations to a carnivorous diet, as the name of the clade suggests, and which are still present in many extant Carnivora (the panda being a well-known exception).
Together with many other groups of mammals, Carnivora are part of a clade named Laurasiatheria thus named because they may have originated in the Laurasia supercontinent, which comprises nowadays north America and Eurasia.