The leaves of Gardenia cornuta grow in whorls of three at the often thorny branchlet ends. They are obovate, shiny green above and hairless.
The flowers grow singly at branchlet tips. They are white, becoming yellow as they age. The corolla tube is long and thin, opening in five long, spreading lobes. The flower base is enveloped by a green calyx comprising six narrow, twisting lobes. The flowers are strongly aromatic.
The fruit is ovoid in shape, orange or brown in colour. The calyx persistent at its tip. The bark is pale greenish-grey, mottled and sometimes flaking (Coates Palgrave, 2002).