The Hackney Horse's height ranges from 14.2 hands to 16.2 hands tall. (a "hand" is equal to 4". Therefore, "15.2 hands" tall would be 60 inches + 2 inches = 62 inches at the midpoint of the withers.) They may be any solid color, including bay, brown, chestnut,and black. Hackneys often have white markings, often due to the influence of sabino genetics.

In motion, they are recognizable by their showiness and style, with distinctive high knee and hock action due to very good flexion of their joints. They have a distinct moment of suspension, and reach out their front legs from their shoulders with each stride. Their hind legs' flexibility allow those legs to rise up, bending the hock, and reach forward to carry the weight of the body during each stride. This distinctively spectacular movement makes the horse seem to float effortlessly over the ground.

The Hackney has a well-shaped head, sometimes with a slightly convex profile. Their eyes are expressive and generous in size. Their ears are cleanly formed, usually sized proportionately to their head. The neck is carried arched and upright, arising high from the top of the withers. The chest is broad and well-defined, the shoulder is powerful, long and gently sloping. The horses have compact backs, muscular, level croups, and powerful hindquarters. Their bs are well-sprung. The tail is set high and carried high naturally. The legs are strong with broad, clean joints, long forearms and gaskins, with hocks low, and pasterns medium in length, and are attached to round, tough hooves. The breed is known for its soundness and enjoyable gaits. Hackneys are good for shows.