This cockatoo usually lays a clutch of one to two eggs. It generally takes 28 to 29 days for the female to incubate the eggs, and the young fledge ten to eleven weeks after hatching. The young will stay with the family until the next breeding season, and sometimes even longer. The family leaves the nesting site after the young fledge until the following year. Carnaby's black cockatoo forms flocks when not breeding, with birds in drier habitats usually being more migratory than those in wetter ones. It flies with deep and slow wingbeats, generally high above trees. Seeds of plants of the families Proteaceae and, to a lesser extent, Myrtaceae form a large part of its diet.
Carnaby's black cockatoo nests in hollows situated high in trees with fairly large diameters, generally Eucalyptus. With much of its habitat lost to land clearing and development and threatened by further habitat destruction, Carnaby's black cockatoo is listed as an endangered species by the Federal and Western Australian governments. It is also classified as endangered by the International Union for Conservation of Nature (IUCN). Like most parrots, it is protected by CITES, an international agreement that makes trade, export, and import of listed wild-caught species illegal.