Cyanea remyi is a shrub that grows 0.9–2 meters tall, characterized by an unbranched stem (occasionally with 1 or 2 branches from the base), 1–2.5 cm in diameter, erect, unarmed, with the apex dark purple and pubescent and the base brown and glabrous. It exudes light yellow (sometimes white) thin latex. The leaves are simple and alternate, with broadly elliptic, ovate, or oblong blades measuring 16–40 cm in length and 9.5–19.5 cm in width. The leaf apex can be obtuse, acute, acuminate, or cuspidate, while the base ranges from subcordate to rounded. The upper surfaces are green and glossy with a maroon or dark purple midrib, and the lower surfaces are whitish green and shiny, with scattered short white hairs along the midrib and veins. Margins are minutely callose–denticulate, with 8–20 cm long petioles, maroon or dark purple, and variably glabrous or pubescent. The flowers are in a pubescent, ascending inflorescence of 6–13 flowers, with a peduncle 4–8 cm long and maroon or dark purple. The hypanthium is obovoid or obconic, 9–12 mm long, dark purple, and pubescent. Calyx lobes are triangular, dark maroon, 4–6 mm long. The corolla is bilabiate, dark purple, 40–53 mm long, densely pubescent, with a curved tube and linear lobes that are purplish white on the inner surface towards the apex. The stamens are connate, with a slightly exserted staminal column and purplish-white filaments. The ovary is inferior, 2-celled, with a two-lobed stigma that becomes receptive after pollen is pushed out. The spherical berries are 10–13 mm in diameter, maroon or dark purple with orange flesh, and tuberculate. The numerous, minute seeds are black or dark brown, smooth, and shiny. It is found on wet seeping or saturated rocky substrates in rainforest and shrubland areas at 370–770 meters.