Persoonia microphylla is an erect to prostrate shrub that typically grows to a height of about 2 m (6 ft 7 in) and has smooth bark, its young branchlets covered with whitish or greyish hairs. The leaves are broadly elliptical to broadly egg-shaped, 3–9 mm (0.12–0.35 in) long and 2–5 mm (0.079–0.197 in) wide with the edges turned downwards. The flowers are arranged in groups of up to fourteen along a rachis up to 30 mm (1.2 in) long that grows into a leafy shoot after flowering. Each flower is on a pedicel about 1–3 mm (0.039–0.118 in) long, usually with a leaf at the base. The tepals are yellow, 8–10 mm (0.31–0.39 in) long and hairy on the outside. Flowering occurs from December to February and the fruit is a green drupe with purple stripes.^[2][3][4][5]

Persoonia microphylla was first formally described in 1830 by Robert Brown in the 1830 supplement to his Prodromus from specimens collected in 1823 near Port Jackson by "D. Cunningham".^[6][7]

This geebung grows in heath and forest in eastern New South Wales at altitudes between 600 and 1,200 m (2,000 and 3,900 ft), occurring disjunctly near Taralga and in river catchments of the Budawang Range.^[3]