Geranium multiflorum is a compact, many-branched shrub, reaching heights of 10–20(–30) decimeters. Its stems are gray to reddish or dark gray, with branches covered with persistent stipules and leafy only at the apex. The leaves are simple and alternate, with ovate to elliptic or occasionally obovate blades measuring (3.2–)4.5–7(–9.9) cm in length and 1.5–3(–3.8) cm in width, featuring an acute to rounded apex. The upper surfaces of the leaves are green and range from glabrous to moderately or densely silky strigose, while the lower surfaces are densely grayish-green to gray silky strigose. The leaves have serrate margins with 7–15 teeth on each side, usually 7–11-veined. Petioles measure (1–)1.5–2.5(–3) cm, and the plant has subulate stipules 7–10 mm long. The flowers are prolific, usually with 25–50 in compound cymes forming large corymbose inflorescences extending beyond the leaves. The peduncles are 1.5–3 cm long, and the flowers are actinomorphic and perfect. Pedicels measure 0.3–0.8 cm long, elongating up to 1 cm in fruit, and narrow bracts subtend each. The calyx comprises 5 sepals, often purple-tinged and 6–9 mm long. The petals are white, often with purple veins, or can be pink to dark purple, and are 10–15 mm long. It has (5)10 stamens, and the ovary is superior, with a complex reproductive structure that leads to a unique seed dispersal mechanism via elastically dehiscent capsules. The fruit is a septicidal and elastically dehiscent capsule that breaks into segments, each containing 1–2 dark reddish-brown, oblong-obovoid seeds about 2 mm long. The seed surface is reticulate, with a scanty or absent endosperm. It is found in rare to scattered populations within montane grassland to wet forest, occasionally extending into subalpine shrubland between 1,580–2,450 meters.