Polyscias hawaiensis is a tree species that spans 7 to 20 meters in height. Its leaves are compound and arranged alternately along the stems, with blades stretching 20–60 cm long. Each blade bears 5 to 9 leaflets that are narrowly ovate to oblong-elliptic, measuring 10–18 cm in length and 3.5–7 cm in width, with the base pair often appearing smaller and more ovate. The apices of the leaflets range from rounded to nearly acute, while the bases are cuneate to truncate, exhibiting an oblique shape for lateral leaflets. The lower surfaces of the leaflets are distinguished by their dense yellowish-brown stellate farinose covering, though younger foliage may be farinose throughout. The margins of the leaflets are entire and attached to the stems via petiolules that are 5–20 mm long. Stipules are either absent or rudimentary, further defining the leaf structure. The flowers are organized in terminal umbellules with one to a few lateral ones along ultimate branches, exhibiting an erect, racemose-umbellate inflorescence structure with primary branches reaching up to 35 cm long. The flowers are bisexual and actinomorphic, showcasing yellowish-green petals that may be tinged reddish externally, measuring 5–8 mm long. The inferior ovary contains 7 to 13 carpels, topped by a low-conical to flat, pale green nectary disk. The styles are fused into a stylopodium, crowned by a ring of stigmatic bulges. The fruits are globose to depressed-globose drupes, measuring 5–8(–10) mm long, with a distinctive whitish stellate farinose covering. The seeds are single per pyrene, with a small embryo. It occurs in mesic to wet forests between 150-800 meters.