The stork is glistening black overall with a black "skull cap", a downy white neck which gives it its name. The lower belly and under-tail coverts are white, standing out from the rest of the dark coloured plumage. Feathers on the fore-neck are iridescent with a coppery-purple tinge. These feathers are elongated and can be erected during displays. The tail is deeply forked and is white, usually covered by the black long under tail coverts. The African birds are described as having the edges of the black cap diffused or with a jagged border compared to a sharp and clean border in the Asian birds. Sexes are identical, though males are thought to be larger. When the wings are opened either during displays or for flight, a narrow band of very bright unfeathered skin is visible along the underside of the forearm. This band has been variously described as being "neon, orange-red", "like a red-gold jewel", and "almost glowing" when seen at close range.
It is a widespread tropical species which breeds in tropical Africa. It is a resident breeder in wetlands with trees. They use a variety of freshwater wetlands including seasonal and perennial reservoirs and marshes, crop lands, irrigation canals and rivers. They use coastal areas in Africa also, with birds in Sulawasi observed to be eating sea snakes, and birds on the Kenya coast foraging in coral reefs and mudflats.
Several calls by adult birds have been described including bisyllabic whistles given along with displays at the nest, and a fierce hissing sound when a bird was attacked by a trained falcon. The woolly-necked stork is a broad winged soaring bird, which relies on moving between thermals of hot air for sustained long distance flight. This species is largely solitary or seen in pairs or small family groups of 4-5, and flocks are rare. In agricultural landscapes, the species occurs mostly as very small flocks (< 5 birds), though flocks of over 10 birds occur commonly.
The woolly-necked stork walks slowly and steadily on the ground seeking its prey, which like that of most of its relatives, consists of amphibians, reptiles and insects. The large stick nest is built on a tree, and two to five eggs form the typical clutch, with five eggs being very rare. Birds commonly use both forest trees and solitary trees in agricultural areas to build nests. Riverside cliffs are also increasingly being used as nest sites