Eurya sandwicensis is a small tree or shrub, sometimes sprawling in windswept sites, with stems 2–6 meters long and strigose branchlets. The leaves are simple, alternate, and closely spaced, with oblong, elliptic, or narrowly obovate blades measuring (2.5–)3.5–9 cm in length and (1.2–)1.5–4 cm in width. The apex is obtuse to rounded, sometimes acute, with a subcordate to truncate or cuneate base. The upper surfaces are glabrous, while the lower surfaces are sparsely strigose along the midrib, and the leaves are coriaceous with reddish veins and conspicuously reticulate under surfaces. Margins are closely serrulate with inflexed, mucronulate teeth. Petioles are (1–)2–3 mm long, and stipules are absent. The flowers are unisexual, appearing 1–2 in the leaf axils, nodding, with pedicels about 5 mm long and ± strigose. The calyx has five purplish brown, thick–coriaceous, suborbicular, and unequal sepals, 3–4 mm long, ± strigose, imbricate, and persistent, enlarging to about 8 mm long in fruit. The corolla comprises five pale yellow to cream, somewhat fleshy, obovate petals, 5–6 mm long, connate at the base. Staminate flowers feature 10–15 stamens in a single series; filaments are distinct, adnate to the base of the petals with nectaries at the base, approximately half as long as the anthers, which open by longitudinal slits. Pistillate flowers have 5–6 staminodes, each 2–3 mm long. The superior ovary in pistillate flowers is 2–6-carpellate, 3–4-celled with axile placentation and 4–60 ovules per cell, and has 3–4 styles. The fruit is a globose berry, dark bluish-black, 7–10 mm in diameter, containing numerous, non-winged seeds with an endosperm. It grows in mesic to wet and diverse mesic forests, often on ridges, at elevations of 400–1,600 meters.