It is a small, brownish bird with a distinctive yellow rump and thin dark bill.

The yellow-rumped thornbill was described as Saxicola chrysorrhoa by the French naturalists Jean René Constant Quoy and Joseph Paul Gaimard in 1830, from a specimen collected in King George Sound.

[6] The species is also reported to be an accomplished mimic of other birds, in particular mimicking the alarm calls of the noisy miner.

The species inhabits a wide range of habitats, including open forest and woodland, grasslands, savannah and scrubland.

The yellow-rumped thornbill is insectivorous; major prey items include ants, beetles, bugs and lerps.

The species usually forages in small groups of between 3-12 individuals, and may join mixed species-flocks with other small insectivorous passerines such as the speckled warbler (Pyrrholaemus sagittatus), weebill (Smicrornis brevirostris), and other species of thornbill.

The nest is a messy dome-shaped structure made of dried grass and other vegetation hidden low down among dense foliage or shrubs, or sometimes in vines or mistletoe.