Boronia megastigma is a shrub that typically grows to a height of 1–2 m (3–7 ft) and has slender branches covered with fine, soft hairs.

The leaves are sessile with three or five thick, slender, linear leaflets 10–20 mm (0.4–0.8 in) long and strongly aromatic.

[2][3][4][5][6] Boronia megastigma was first formally described in 1848 by Friedrich Gottlieb Bartling and the description was published in Lehmann's book Plantae Preissianae.

All of the organs of the flower contain oil glands and their activity is greatest while the stigma is receptive to pollen, which suggests that production of scent may serve to attract pollinators such as insects.

Over-exploitation in natural habitat areas of Southwest Western Australia has caused re-examination of over cropping in the wildflower industry.