Notelaea sandwicensis is a tree that can grow up to 8 meters tall and sometimes even reach 25 meters. It is notable for its thick, corrugated bark. The leaves are simple and opposite, with lanceolate to elliptic-lanceolate or narrowly elliptic blades that measure 7–22 cm in length and 2.2–6 cm in width, occasionally up to 7 cm. The leaf apex ranges from acute to acuminate and is rarely obtuse, with a rounded base to cuneate. The upper surfaces of the leaves are glossy, glabrous, and dotted with glands, while the lower surfaces are dull, pale, and range from glabrous to sparsely puberulent along the veins. The leaves also feature glandular-dotted peltate glands and are coriaceous. Leaf margins are entire and not thickened. Petioles are 0.6–1.3 cm long and thickened toward the base. Stipules are absent. The flowers are arranged in axillary, decussate inflorescences that initially measure around 24 cm long and elongate to 3–7 cm long when in fruit. The inflorescences range from glabrous to densely puberulent. Pedicels are 3–4 mm long, elongating to 5–9 mm in fruit, with lanceolate to ovate, slender, and caducous bracts about 1.5 mm long. The flowers are bisexual (perfect) and actinomorphic (radially symmetric), featuring a short, 4-toothed calyx with teeth approximately 0.6–1.1 mm long. The corolla is 4-lobed, rotate, approximately 2–3 mm long, and the stamens are inserted on the corolla tube. The ovary is superior, 2-carpellate, 2-celled with axile placentation, and ovules numbering 2 per cell; the stigma is 2-lobed and dry. The fruits are green drupes when immature, turning purplish and then bluish-black upon maturation. They are rather dry, ovoid to ovoid-conical, and measure 1.6–2.2 cm long. Each fruit typically contains one seed. It is found in dry to mesic forests between 30-1,300 meters.