Impala are diurnal, most active shortly after dawn and before dusk. They spend the night feeding and resting. They use various kinds of unique visual, olfactory and auditory communication, most notably laying scent-trails and giving loud roars.The roaring process consists of one to three loud snorts with mouth closed, followed by two to ten deep grunts with an open mouth, lifted chin and upraised tail. The most characteristic movement of the impala is its unique leap. When alarmed, they run at very high speeds and jump to heights of 3 m (9.8 ft), over bushes and even other impala, covering distances of up to 10 m (33 ft). The impala has an average lifespan of about 15 years in the wild, and nearly 17 years in captivity.

It is a sexually dimorphic antelope; only males are horned, and they are noticeably larger than the females. The head-and-body length for the species as a whole is typically between 120–160 cm (47–63 in). Males reach approximately 75–92 cm (30–36 in) at the shoulder, while females reach 70–85 cm (28–33 in). Males typically weigh 53–76 kg (117–168 lb) and females 40–53 kg (88–117 lb).

The coat is a glossy reddish brown. The red hue fades away towards the animal's sides and the underside is white. Facial features include white rings around the eyes, as well as a light chin and muzzle. There are black stripes on the forehead, rump and tail. The ears are also tipped with black.

Impala are important prey animals for several carnivores, including lions, leopards, cheetahs, Cape hunting dogs, spotted hyenas, crocodiles and pythons.

An alert and wary animal, the impala turns motionless on sensing danger. It will scan the vicinity with its eyes to spot the predator, and rotate its ears to catch any tell-tale sounds. It stares at and moves its head to get a better view of any object it can not identify. The female who leads a file of impala on the way to drink often stops and surveys the surroundings for danger, while the rest stand relaxed. Unlike other antelopes, who run away in the open when disturbed, the impala tries to hide itself in dense vegetation in case of any alarm.