Cyathea hornei is a species of tree fern. Its natural distribution covers eastern New Guinea and the Louisiade Archipelago to Fiji, where it grows in wet submontane forest, stunted forest, mossy forest, and on ridges, at an altitude of 400–2000 m. The trunk of this plant is erect, 3–4 m tall and up to about 4 cm in diameter. Fronds may be pinnate or bipinnate and reach a length of 2 m. Basal scales cover the dark rachis and stipe of this species. These scales are glossy and either bicoloured (dark with a paler margin) or light brown and bullate. Sori almost cover the lower segments of fertile pinnules. Indusia are absent.