It is a member of the seedsnipe family, a group of small gregarious waders which have adapted to a vegetarian diet of seeds and other plant material. The most common food is the buds and leaf tips of cushion plants. It is found in the high Andes at up to 4000 m, although it can occur as low as 1000 m in the south of its range. It is very hardy, and does not move downhill even in harsh conditions.

Rufous-bellied seedsnipe, when on the ground, looks superficially like a partridge in structure and bill shape. It has short legs and long pointed wings, and looks much more like a wader or sandgrouse in flight. It is the largest seedsnipe at 27–32 cm (10.5–12.5 in) in length. A very bulky bird, this species weighs 300 to 400 g (11 to 14 oz).

The nominate race which breeds in Chile and Patagonia has scalloped pale rufous underparts, and reddish brown upperparts, with much barring. A.g. latreillii of Ecuador is deeper chestnut below and darker above. A.g. simonsi of Peru, Bolivia and northwest Argentina is intermediate in appearance.

The sexes are similar, and the juveniles are also very much like the adults, although even more heavily barred. The call is a harsh tchaaa.

The rufous-bellied seedsnipe's 2-3 eggs are laid in a shallow scape on the ground, and the young are able to walk and feed as soon as they are hatched.

Rufous-bellied seedsnipes are sometimes hunted for food by local people, especially near mines.

The scientific name of this bird commemorates the French naturalist Claude Gay.