Measuring 10.5–12.5 cm (4.1–4.9 in) in length, the robin has a small, thin, black bill, and dark brown eyes and legs.

The red-capped robin was described by Nicholas Aylward Vigors and Thomas Horsfield in 1827, having been collected in the northern Spencer Gulf in South Australia.

[3] The specific epithet goodenovii honours the Reverend Samuel Goodenough, Bishop of Carlisle and first treasurer of the Linnean Society.

The generic name is derived from the Ancient Greek words petros 'rock' and oikos 'home', from the bird's habit of sitting on rocks.

[10] The female is an undistinguished grey-brown above with a reddish tint to the crown, and paler underneath with dark brown wings and pale buff wing-patch.

Immature birds initially resemble the female;[9] it is only with their second moult, which takes place at around a year of age that males adopt their distinctive adult plumage.

Carotenoids are costly to metabolise, and are also required for use in immune function, hence red-capped robins need to be in good condition to have enough left for use in red feathers.

[22] Female and immature birds are harder to distinguish, but can be differentiated by the reddish tinge of the crown and whiter underparts.

[22] The red-capped robin is found across Australia, except for Tasmania, Cape York, the Top End, and most of the Kimberley (there have been occasional sightings in the southernmost parts).

Although widespread, it is uncommon in many areas; it is rare east of the Great Dividing Range, in coastal regions in the south of the continent, and in the northern parts of its range—it is seldom encountered north of 20°S.

[19] It is sedentary in much of the southern parts of its range, although the red-capped robin is a spring and summer visitor to the Nullarbor Plain and Adelaide region in South Australia, and central Victoria.

[27] It has also disappeared from the vicinity of Rockhampton in Queensland, and declined on Rottnest Island, and in the Wheatbelt region of Western Australia.

[25] The feral cat is known to prey on the red-capped robin, and several bird species, including the Australian raven (Corvus coronoides), grey shrike-thrush (Colluricincla harmonica), grey butcherbird (Cracticus torquatus), and white-browed babbler (Pomatostomus superciliosus) raid nests and take young.

[32] The red-capped robin typically perches in a prominent location low to the ground, often flicking its wings and tail.

[35] Two males have been seen to face one another 30 to 1 m (98.4 to 3.3 ft) apart, flicking wings and manoeuvring for position in a threat display, while the female is incubating her eggs.

[35] Most juvenile red-capped robins are unable to live in territories occupied by adult birds, and need to travel to find unoccupied land; the furthest dispersal recorded to date has been 36 km (22 mi), from Terrick Terrick National Park across farmland to Gunbower National Park in northern Victoria.

Spider webs, feathers, and fur are used for binding or filling, and the nest is generally placed in a tree fork, or sometimes a mistletoe bush.

[30] The male will keep lookout either on the nest or perched on a nearby branch, rather than brood, while the female is foraging; and both parents will feed young and dart off quickly, if there are predators in the vicinity.

[30] Parents feed young for at least three weeks after leaving the nest,[30] and have been recorded giving them spiders, and insects, such as flies and moths.

[35] The long breeding season and multiple broods therein are an adaptation to mild climate and high levels of predation.