The male eastern spinebill is 13–16 cm (5–6.5 in) long, and has a long thin down curved black bill with a black head, white throat with a reddish patch and red iris. It has a brownish-red nape, a grey brown back and pale cinnamon underparts. The dark tail is tipped with white laterally. Females and juveniles are smaller and duller. The call is a rapid piping.[8]

Breeding season is from August to December, with one or two broods raised. The nest is a deep cup-shaped structure of grass and bark lined with feathers, generally in the fork of a small bushy tree or shrub. The clutch is one to four, with two being the average, pinkish eggs with dark reddish brown blotches and spots 17 x 13 mm in size. The female incubates the eggs for 13 to 16 days before hatching. Both parents feed the chicks and remove the faecal sacs from the nest.