The Gang Gang Cockatoo has a relatively restricted distribution in South-eastern Australia and is mainly found in the higher altitude old growth eucalypt forests. In winter it may move down into lower altitude woodlands and even into settled areas such as Canberra. The seeds of the forest eucalyptus and acacias make up most of the diet, supplemented by other plant material and insects. In summer it is usually seen in family groups but may flock together in winter, especially when feeding amongst berry-laden trees and shrubs. In Canberra in winter it is especially fond of Cotoneaster and hawthorn (Crataegus) berries and flocks of 20 or more are not uncommon.
The breeding season extends from October to January, with a hollow high in a eucalypt tree being used. Two, or more rarely three, eggs are laid and both parents share incubation.
Although traditionally linked to the Black Cockatoo group recent biochemical work has shown it to be more closely related to the Galah and white cockatoo group than to black cockatoos. It has been known to hybridise with the Galah, and an example of hybridisation in the wild with an escaped Little Corella has been reported.