Cyanea kunthiana is a shrub reaching 0.5–1.5 meters in height with sub-herbaceous stems that are woody at the base, either unbranched or sparingly branched. The leaves are simple, alternate, elliptic to narrowly obovate, measuring 12–30 cm long and 3–7 cm wide, with an acuminate apex and cuneate base. The upper leaf surfaces are green and sparsely pubescent, while the lower surfaces are whitish green and pubescent, with minutely callose-denticulate margins. The petioles are 2–4 cm long. The inflorescences comprise 8–24 flowers, axillary and pubescent, with peduncles 6–25 mm long and pedicels 6–15 mm long. The hypanthium is obovoid and pubescent, measuring 4–6 mm long. The flowers are bisexual, with a 5-lobed calyx whose lobes are narrowly triangular, 5–8 mm long, and an acuminate apex. The corolla is zygomorphic (bilaterally symmetric), whitish with pale lilac longitudinal stripes or dark purplish, 30–35 mm long and 3–4 mm wide, sparsely pubescent, with the tube being suberect to slightly curved and lobes spreading. There are five stamens, which are connate and alternate with the corolla lobes, with a sparsely pubescent staminal column and densely pubescent anthers. The fruits are purplish orange, obovoid to ellipsoid berries measuring 7–8 mm long. They contain numerous small, brown to black seeds that are smooth and shiny, ca. 0.5(–2) mm long, with a straight, short, to spatulate dicotyledonous embryo embedded in oily endosperm. It occurs in wet forest habitats at elevations of 1,000–1,600 meters.