Gymnosphaera hornei is a species of tree fern in the Cyatheaceae family.

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.

[5] The specific epithet hornei commemorates botanist John Horne (1835-1905), who collected numerous plants on Fiji and islands of the Indian Ocean.

[5] It is listed as a least-concern species by the International Union for Conservation of Nature.