King cobras are most noted for their venom, which is located in salivary glands behind the eyes — these glands are attached to two hollow, erect fangs. These fangs are ½ inch (12 mm) in length and are attached to the upper jaw. The lower jaw consists of two bones loosely hinged together, which can allow large prey to be swallowed.

King cobras have good eyesight, being able to see 330 ft (100 m) away. They lack external ears, but can still hear due to sound traveling through their skin to the jaw bone, then to the quadrate bone (next to the ear bone), and from there to the inner eardrum. They taste and smell with their forked tongue, drawing scents into their mouth which are then recognized by the Jacobson's organ. Holes in the trachea emit a low hiss resembling a dog's growl.

King cobras are more intelligent than true cobras, being able to distinguish their caretakers from strangers. They have a life span of 20 years.