Cyrtandra lydgatei is a shrub that grows to a height of 1–2.5 meters. The stems are either unbranched or few-branched, and they have a rounded to angular shape with a pubescent surface with multicellular hairs or sometimes smooth (glabrate). The leaves are simple and opposite, typically found on the upper 3–6 nodes. Each pair of leaves is unequal but symmetrical, with shapes ranging from broadly elliptic to suborbicular and sizes from 13 to 23 cm in length and 4.5 to 14 cm in width. The leaves have an acuminate apex and a base that is either cuneate or abruptly narrows to a long-attenuate form. The upper surfaces are sparsely hirsute, while the lower surfaces are pale and either sparsely puberulent or smooth. The leaves are thin, chartaceous, and often flaccid, with coarsely and sometimes irregularly serrate margins. The petioles are 3–9 cm long and range from sparsely to moderately villous. It does not have stipules. The flowers occur in (2)3–7 dense umbelliform cymes emerging from the leaf axils. These are moderately villous with slender peduncles of 5–14 mm and slender, unequal pedicels of 5–16 mm. The bracts are lanceolate to elliptic, either distinct or occasionally fused, measuring 6–8 mm long. The flowers are bisexual (perfect) and feature a calyx that is 2–5(6)-lobed, actinomorphic or nearly so, green, and 9–15 mm long. The corolla is usually white bilabiate with a cylindrical tube about 8–10 mm long and villous on the upper half. The plant has five stamens, with two upper fertile ones and the others being staminodial. The fruit is a white, ovoid berry measuring 1.3–1.6 cm long, often tipped by the persistent stylar beak. It is found in wet forests between 500-900 meters.