Xylosma hawaiensis is a dioecious or rarely monoecious tree that grows to 3 to 9 meters, characterized by stiff branches without spines. The leaves are simple and alternate, with ovate to broadly elliptic or occasionally lanceolate blades that are thick, chartaceous, or coriaceous in xeric sites, measuring 5 to 21 cm in length and 2.2 to 10.3 cm wide. The apex of the leaves is usually acuminate and slightly falcate, with a base ranging from truncate to occasionally cordate, and the surfaces are glabrous. The leaf margins are glandular crenate or occasionally subentire, and the petioles are usually red. The flowers appear 1 to several in short, racemose cymes, with the plant being dioecious. Staminate flowers are borne on pedicels approximately 1.5 to 2.5 mm long, featuring a 4-lobed nectary disk, while pistillate flowers are on longer pedicels that elongate in fruit. The calyx in staminate flowers consists of 4 to 5 sepals; in pistillate flowers, 4 to 5 obovate to broadly elliptic sepals. Notably, the species lacks a corolla, with staminate flowers possessing numerous stamens. The dioecious flowers are greenish or reddish and 6 mm in diameter. Female plants produce abundant berries in the summer and fall that are deep red when ripe and about 1 cm in diameter. The fruit is a deeply reddish-purple berry, broadly ovoid to subglobose, containing a few black, irregularly obovoid seeds that are approximately 4.5-6 mm. long. It is found in mesic forests, dry woodlands, and wet forests between 250-1,220 meters.