Cyanea heluensis is a sprawling shrub up to 3 meters long, with branches that lean or tangle in nearby vegetation and occasionally root when touching damp soil. It has sparse, small prickles on the lower trunk, denser ones on younger stems, and prominent, nearly circular leaf scars. The leaves form leathery clusters at branch tips, with dark green on top and paler underneath. Leaf size ranges from 26–29 cm by 4–6 cm, with an acuminate tip and narrow cuneate base. The upper surface is smooth primarily, while the underside has sparse pubescence, especially on the midrib. Leaf margins are shallowly lobed with crenate and undulate patterns. Petioles are 3–4 cm long, sparsely prickly, and pubescent. Juvenile leaves are less lobed than adults but still rounded at the apex. Inflorescences grow in leaf axils, near lower leaves, with 6–15 mm long peduncles, carrying 5–10 flowers. Peduncles are primarily smooth but can be slightly pubescent. Bracts and bracteoles are expected to fall off. Bracteoles are around 1 mm, lanceolate to elliptic, and sparsely pubescent. Pedicels are pubescent, 5–9 mm long, and usually have 1–2 bracteoles persisting on their basal portion. Calyx is green with 4–6 mm long deltate lobes, crenate, and undulate margins, occasionally sparsely pubescent, and possibly purple in live specimens. Corolla is white with muricate projections, 45–55 mm long by 4–5 mm wide, and lobes about one-third the tube’s length. Hypanthium is 4–5 mm long and 4–5 mm wide, sparsely pubescent. Berries are small, globose, 5–10 mm in diameter, with orange sepals that fall off as they mature. Seeds are brown, smooth, round to ellipsoid, and less than 1 mm in size. It occurs in lowland wet forests, at ca. 1268 m.