It has smooth bark, young branches with conspicuous flanges, narrow elliptical leaves, white flowers and thin-walled, bell-shaped to hemispherical fruit.

Aggreflorum benwellii is a shrub that typically grows to a height of 3 m (9.8 ft) and has smooth bark that is shed annually.

The flowers are borne singly or in groups of up to three in leaf axils on pedicels about 1 mm (0.039 in) long.

[2][3] This species was first formally described in 2004 by Anthony Bean who gave it the name Leptospermum benwellii in the journal Telopea from specimens he collected near Munningyundo in the Nymboida National Park.

[2][4] In 2023, Peter Gordon Wilson transferred the species to the genus Aggreflorum as A. benwellii in the journal Taxon.