Adult Cape Barren geese are large birds, typically measuring long and weighing between , with males generally being larger than females. The plumage is mostly pale grey with a slight brown tint. The head is somewhat small in proportion to the body and mostly grey in colour, save for a pale whitish patch on the forehead and crown. The bill is short, measuring in length, triangular in shape and black in colour with a prominent pale yellow-green
cere covering more than half the length of the bill. Feathers on the breast and back have pale margins, while the upperwing
coverts and scapular feathers each have a brownish grey spot near the tip. The
flight feathers are grey with black tips, with the black extending to cover the distal half of the outer primaries, giving the appearance of a dark trailing edge to the wings when in flight. The tail feathers are black, and the legs are pink with black feet. Newly-hatched goslings are white with broad, dark stripes and a dark cere. Older juveniles are a paler grey with heavier spotting on the wings and scapular feathers than adults. The cere turns a light yellow-green colour at around 70 days old, with juveniles molting into adult plumage at around 6 months old. Cape Barren Nest with Eggs.JPG|Nest with eggs,
Cleland Wildlife Park Cereopsis novaehollandiae -Phillip Island, Victoria, Australia -gosling-8.jpg|Gosling,
Phillip Island Cereopsis novaehollandiae Juvenile.jpg|Juvenile,
Maria Island Cape Barren goose (Cereopsis novaehollandiae) pair with juvenile Maria Island.jpg|Pair with juvenile,
Maria Island Cereopsis novaehollandiae - Orielton lagoon.jpg|Pair,
Orielton Lagoon Cape Barren goose (Cereopsis novaehollandiae) Kangaroo Island.jpg|Adult,
Kangaroo Island Cape Barren geese (Cereopsis novaehollandiae) in flight Kangaroo Island 2.jpg|Adults in flight,
Kangaroo Island Cape Barren Goose (Cereopsis novaehollandiae) (2).jpg|Head of adult, showing distinct bill ==Behaviour==