The sable antelope has a compact and robust build, characterized by a thick neck and tough skin. It has a well-developed and often upright mane on its neck, as well as a short mane on the throat. Its general colouration is rich chestnut to black. Females and juveniles are chestnut to dark brown, while males begin darkening and turn black after three years. However, in southern populations, females have a brown to black coat. Calves less than two months old are a light tan and show faint markings. The underparts, cheek, and chin are all white, creating a great contrast with the dark back and flanks. Long, white hairs are present below the eyes, and a wide, black stripe runs over the nose.
Both sexes have ringed horns which arch backward.