The orange-bellied parrot is a small parrot around 20 cm (8 in) long; the adult male has bright green head, neck and upperparts, and yellow-green breast, abdomen and flanks.
The feathers of the cheeks, neck and underparts are yellow-green with lime green tips and fringes, and hence appear more bright green when the bird has just moulted and more yellowish as the plumage wears.
Feathers on the crown are bright green with darker green tips.
It has a prominent, two-toned blue frontal band, with a lighter blue border both above and below the horizontal dark blue band.
On the belly is an oval patch of orange around 2 cm in diameter.
The undertail coverts are yellow to pale yellow.
The uppertail is green-blue with yellow sides.
The under wing-coverts and flight feathers are dark blue, with paler blue median wing-coverts.
The upper mandible of the bill is blackish grey with a greyish, orange-brown or salmon-coloured base and cutting edge, while the lower mandible a brownish orange a grey-black tip.
The cere is blackish grey with a pale brown tinge around the nostrils, the orbital eye-ring is light grey and the iris is dark brown.
The legs and feet are dark grey with a red tinge between scales.
The adult female has slightly duller shades of green plumage overall, with a paler blue frontal band.
Its orange belly patch is about 30% smaller and less distinct.
Moulting takes place in late winter and early spring.

The juvenile is a duller green to yellow-olive colour overall, with a much less prominent blue frontal band above the eyes.
It has a dull yellowish or orange bill, which darkens to brown by the time the bird is three months old.

The orange-bellied parrot most commonly utters a single-note buzzing sound that is repeated every one to three seconds as a contact call.
This is generally made orange-bellied parrots while flying, but also by birds seeing others in flight.
The alarm call is a quickly repeated tzeet that has a buzzing quality.
Individuals may make this call when flushed from cover.
The gurgle-buzz call is made by birds acting as sentries at feeding areas, and is a mixture of an alarm call interspersed with chattering and hissing.
When feeding, orange-bellied parrots may make soft low-pitched chitting sounds.

The blue-winged and elegant parrots can be mistaken for the orange-bellied parrot, however their tinkling alarm calls and lighter olive-green upperparts distinguish them.
Their blue frontal bands have only light blue border on one side.
The orange-bellied parrot is a small parrot around 20 cm (8 in) long; the adult male has bright green head, neck and upperparts, and yellow-green breast, abdomen and flanks. The feathers of the cheeks, neck and underparts are yellow-green with lime green tips and fringes, and hence appear more bright green when the bird has just moulted and more yellowish as the plumage wears. Feathers on the crown are bright green with darker green tips. It has a prominent, two-toned blue frontal band, with a lighter blue border both above and below the horizontal dark blue band. On the belly is an oval patch of orange around 2 cm in diameter. The undertail coverts are yellow to pale yellow. The uppertail is green-blue with yellow sides. The under wing-coverts and flight feathers are dark blue, with paler blue median wing-coverts. The upper mandible of the bill is blackish grey with a greyish, orange-brown or salmon-coloured base and cutting edge, while the lower mandible a brownish orange a grey-black tip. The cere is blackish grey with a pale brown tinge around the nostrils, the orbital eye-ring is light grey and the iris is dark brown. The legs and feet are dark grey with a red tinge between scales. The adult female has slightly duller shades of green plumage overall, with a paler blue frontal band. Its orange belly patch is about 30% smaller and less distinct. Moulting takes place in late winter and early spring.
The juvenile is a duller green to yellow-olive colour overall, with a much less prominent blue frontal band above the eyes. It has a dull yellowish or orange bill, which darkens to brown by the time the bird is three months old.
The orange-bellied parrot most commonly utters a single-note buzzing sound that is repeated every one to three seconds as a contact call. This is generally made orange-bellied parrots while flying, but also by birds seeing others in flight. The alarm call is a quickly repeated tzeet that has a buzzing quality. Individuals may make this call when flushed from cover. The gurgle-buzz call is made by birds acting as sentries at feeding areas, and is a mixture of an alarm call interspersed with chattering and hissing. When feeding, orange-bellied parrots may make soft low-pitched chitting sounds.
The blue-winged and elegant parrots can be mistaken for the orange-bellied parrot, however their tinkling alarm calls and lighter olive-green upperparts distinguish them. Their blue frontal bands have only light blue border on one side.
Orange-bellied parrot