Coprosma foliosa is a dioecious, scandent (climbing habit) shrub or small tree 1-8 m tall. The stems of this species are characterized by their many branches or sometimes just a few short branches in scandent forms. Younger stems vary from puberulent to glabrous, with pilosity noted in specific locations such as East Maui. The leaves are simple and arranged oppositely. They can be closely spaced or more widely so in scandent forms. Leaf blades exhibit a variety of shapes, including lanceolate to narrowly ovate, elliptic–lanceolate, elliptic, or oblanceolate, and range significantly in size from 20 to 110 mm in length and 5 to 30 mm in width. The apex of these leaves can be acuminate to acute, with some being obtuse or rounded, and the base ranges from cuneate to attenuate. Leaf surfaces are mostly glabrous, though the upper surfaces may be sparsely puberulent along the midrib, with the lower surfaces showing similar characteristics and occasionally on lateral veins. The leaves are chartaceous, with ciliate margins and pinnately veined. Petioles are 3–23 mm long and can be either puberulent or glabrous. Stipules are narrowly deltate and vary in connation, being glabrous or puberulent at the base, with short-pilose margins. The flowers are 1–3 per cluster, situated axillary, with 6-10 merous flowers supported on peduncles that are 3–15 mm long and can be either glabrous or puberulent. The species is dioecious and often heterostylous, relying on insects for pollination. The calyx and corolla of staminate and pistillate flowers vary slightly in shape and size, with the nectary disk usually present. The reproductive structures, including stamens and ovaries, exhibit traits that facilitate pollination and subsequent fruit development. The fruit is a drupaceous, juicy berry, bright orange to reddish-orange, and ovoid, measuring 6–9 mm long. It contains 2(-4) one-seeded, planoconvex pyrenes, with an apex marked by the inconspicuous persistent calyx. Seeds have a well-developed oily endosperm, although, in some instances, the endosperm may be scanty or absent. It thrives in mesic to wet forest habitats, sometimes found on ridges, indicating its preference for moist environments. The elevation range for this species spans from 300 to 1,830 meters.