The Magpie Goose is distributed in northern Australia and southern New Guinea. See the distribution map at Birdlife International. It used to be widespread in southern Australia but the birds were either shot as an agricultural pest or their swamps were drained and the plants destroyed by grazing cattle. This remains a threat in the north through water buffalo rather than cattle.

A primitive goose, it has proved difficult to classify and it has been suggested in the past that it deserves a family on its own. It differs from most geese and ducks in having only half-webbed feet (hence semipalmata) which might have been an adaptation to perching on trees. It also moults its wing feathers gradually so as to have no flightless period unlike most waterfowl.

A feature of the bird is the large knob on its head. This is usually larger on the male than on the female but is also an indication of age so an older female will have a larger knob than a young male.