The upperparts are sooty black, finely spotted white on the head with larger but sparser white spots on the wings. The Facial disc is large, round and sooty black through to dark grey or silver and is heavily edged black. The Belly is always paler than the breast. The tail is very short, the legs feathered and eyes very large with a black iris. A Sooty Owl's Bill is horn coloured and feathered almost to the tip.
Toes are dark grey and the large talons black.
Sexes are similar in plumage and Females are usually slightly larger than males. They are distinguished from lesser Sooty Owls by much larger size and darker plumage, sparser white spots on upperparts and darker underparts which have white spots on a dark background where the lesser Sooty Owl has dark chevrons on a pale background. The characteristic call is a piercing downscale shriek, lasting for upwards of two seconds. It has been likened to the sound of a falling bomb without the final explosion and the call is now widely known as the 'bomb whistle'. There are also various other calls associated with breeding and nesting.