Cyanea grimesiana subsp. obatae is a shrub that grows to heights of 1–3.2 meters. It features unbranched or sparingly branched muricate stems (covered with small, hard projections). The leaves are simple and alternate, with pinnately divided blades measuring 27–58 cm long and 14–32 cm wide. Each blade has 9–12 segments per side, narrowly elliptic, oblong, or triangular, and 0.8–5 cm wide. The segments have acuminate and apiculate tips, and the leaf’s upper surface is generally glabrous, though it can occasionally be sparsely pubescent or muricate. The lower surface is glabrous or muricate along the midrib and rarely densely pubescent. The margins of the leaf segments are irregularly lobed to cleft, with lobes ranging from acute to obtuse, and the petioles are muricate, measuring 8–32 cm in length. It produces 6–12 flowers in each inflorescence, with peduncles 15–75 mm long and pedicels 20–50 mm long. The flowers are perfect, with an obconical hypanthium 7–16 mm long and 3–8 mm wide. The calyx has five linear to narrowly triangular lobes, 3–13 mm long and 1–2 mm wide, and the corolla is purplish or greenish to yellowish white, often with magenta suffusion or stripes, measuring 55–80 mm in length and 5–10 mm in width. The stamens are five in number and alternate with the corolla lobes, forming a connate staminal column. The anthers, which can be glabrous or sometimes pubescent at the base, feature apical tufts of white hairs and open via longitudinal slits. The inferior ovary is 2-celled with axile placentation, and the stigma is 2-lobed. The fruits are orange, obovoid to ellipsoid berries 18–30 mm long and 8–15 mm wide, topped with persistent calyx lobes. The seeds are numerous, small, brown to black, smooth, and shiny, measuring 0.2–0.5(–2) mm long, with a straight, short to spatulate dicotyledonous embryo embedded in oily endosperm. It is found in mesic to wet forests at elevations of 200–730 meters.