Coprosma pubens is a shrub or small tree reaching heights of 3 to 10 meters. The stems are many-branched and generally glabrous, though they may rarely bear sparse, short hirsute hairs aligned in a line along the stem. The leaves are simple and opposite, with the blades ranging from oblong-elliptic to oblanceolate, and occasionally broadly obovate, measuring 52 to 135 mm long and 15 to 42 mm in width. Leaf apices are acuminate, and bases attenuate to cuneate. The surfaces are glabrous, although some individuals may have sparse pubescence along the midrib near the base. The blades are thin yet coriaceous in texture. Leaf margins are entire, and venation is pinnate but not prominently visible. Petioles measure 6 to 30 mm long and may be pilose on the upper surface. Stipules are 5 to 11 mm long, connate for one-third to one-half their length, and may be glabrous or pilose at the base. Their margins are sparsely to occasionally densely pilose and dentate with a series of appendages. The apex is short-acuminate or attenuate and often ends in a prominent terminal appendage. The flowers occur in clusters of 3 to 5 and are 5- to 8-merous. Peduncles range from 1 to 18 mm long and are glabrous. The species is dioecious with unisexual and often heterostylous flowers, pollinated by insects. In staminate flowers, the calyx is cup-shaped and 0.6 to 1 mm long with irregular whitish, ciliate teeth. The pistillate calyx is also cup-shaped but shorter, at approximately 0.5 mm, and minutely toothed. The staminate corolla is funnelform, measuring 5.3 to 8 mm long, with 2.2 to 3 mm long lobes. The pistillate corolla is more narrowly funnelform and smaller, measuring 3.5 to 5 mm long with lobes around 1.4 to 1.5 mm. A nectary disk is usually present. Stamens number 4 to 5 (rarely up to 10), are alternate with the corolla lobes, and are inserted at the base of the corolla tube. The filaments are long-exserted, and the anthers are pendulous, dithecal, and open via longitudinal slits. The ovary is inferior (occasionally partly so or very rarely superior), typically 2-celled (sometimes up to 4), with one basal anatropous ovule per cell. The style is divided into as many lobes as carpels (2 to 4), deeply divided nearly to the base, and ends in lobed or capitate stigmas that are long-exserted and papillose-hirsute, either dry or occasionally wet. The fruit is a juicy, drupaceous berry, bright orange to reddish-orange, and ellipsoid in shape, measuring 10 to 15 mm in length. The fruit apex is naked and contains 2 to 4 planoconvex pyrenes, each typically 1-seeded. The seeds possess a well-developed oily endosperm, though in some cases, the endosperm may be scanty or absent. It is found in wet and occasionally mesic forests between 360-1,900 meters.