Marianthus granulatus is a species of flowering plant in the family Pittosporaceae and is endemic to a restricted part of the southwest of Western Australia.

Flowering mainly occurs from October to December and the fruit is a blue, egg-shaped capsule about 5 mm (0.20 in) in diameter.

[4][5] In 1863, George Bentham transferred the species to Marianthus as M. granulatus in his Fragmenta Phytographiae Australiae.

[7] Marianthus granulatus is restricted to the Porongorup Ranges in southern Western Australia, where it grows in woodland and forest in creek beds.

[3][2] This marianthus is listed as "Priority Four" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions,[2] meaning that it is rare or near threatened.