West Highland Terriers have bright, deep-set eyes; these tend to be dark, with a "piercing" look. Their ears are generally small, pointed, and erect.

They typically weigh from 15 to 20 pounds (7.5-10 kilograms) and their average height is 11 inches (28 centimeters) at the withers. The Kennel Club has recommended that their tails, typically "carrot-shaped", should never be docked. The tail should be between 5-6 inches.

They also have deep chests, muscular limbs, a huge skull, a short and a closely fitted jaw with "scissors" bite (lower canines locked in front of upper canines, upper incisors locked over lower incisors). Their teeth generally appear quite large for the size of the dog. Westies have a very strong bone structure for their size.

They have a soft, dense undercoat and a rough outer coat, about 2 inches long, that requires regular grooming. Some West Highland Terriers have "wheaten tippings" on their backs, though for individuals put forward for shows this can be regarded as undesirable.

Their paws are slightly webbed and thickly padded.

West Highland Terriers are prone to allergies and dry skin issues, and bathing too frequently may aggravate these problems. Washing once a month or on a longer interval will generally not cause issues. However, frequent brushings are needed to keep the coat clean and oils evenly distributed throughout the coat. Washing with a detergent-free, baby-oriented, or another soft skin shampoo will help keep a West Highland Terriers skin hydrated. Weekly washing of the inside of the ears with cotton balls will prevent oil and wax build-up and ear infections.

Like most other dogs, West Highland Terriers generally require 13 hours of sleep out of every 24. Westies will usually conform to the sleep patterns of their human companions, and take several naps during the day as well, to accrue their needed sleep. Since they are independent, they can withstand moderate periods of time being alone.