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

It is an erect, multi-stemmed shrub with elliptic to oblong leaves and pale blue to almost white flowers arranged singly in leaf axils.

[3] This species of shrub grows in open woodland on sandy loam over laterite on rock outcrops and slopes, and is restricted to the Bremer Range in the Coolgardie bioregion of inland Western Australia.

[4][6] Marianthus aquilonaris is listed as "Threatened" by the Government of Western Australia Department of Parks and Wildlife and an interim recovery plan has been prepared.

The main threats to the species include mining exploration, vehicle movement and track maintenance, and inappropriate fire regimes.