Head and body length of M. fuliginosus is 0.9-1.4m with tail lengths of 75-100cm. Weights range from 15-54kg with adult males reaching twice the size of adult females. M. fulginosus is one of the largest and most abundant kangaroos. It has thick, coarse fur with color variations from pale gray to chocolate brown. The chest and belly are paler.

Western grey kangaroos are capable of using several different types of habitats. They can be found in woodlands, open forests, coastal heathland, and open grassland areas.

M. fuliginosus uses all four limbs when moving slowly, employing its powerful tail as a brace, but uses only its back legs when bounding at high speeds. Males have been known to span a distance of 10m in one leap. M. fuliginosus lives in stable groups of up to 15 individuals. Battles for females during mating season and food or resting sites may occur between males from the same social group. The dominant male is usually the only male to breed. Females have one baby or joey after an incubation period of 30-31 days, and the baby remains in its mothers pouch attached to the teat for 130-150 days. At 250 days the joey begins to leave the pouch for short periods, but returns quickly if danger is near.

Western Grey Kangaroos eat grasses, forbs, leaves, tree bark, and shrubby browse. They use microorganisms in an organ called the cecum to digest the cellulose of plants. This kangaroo requires very little water and is able to survive on plants high in fiber. Western grey kangaroos spend between 6 and 10 hours grazing per day, mostly at dawn and dusk.

They are found in SW New South Wales, NW Victoria, South Australia, SW Western Australia, Tasmania, King Isl, and Kangaroo Isl (Australia).