Patersonia maxwellii is a species of flowering plant in the iris family Iridaceae and is endemic to the south of Western Australia.

It is a tufted, rhizome-forming perennial herb with linear leaves and violet tepals.

Flowering occurs from September to November and the fruit is a capsule 20–25 mm (0.79–0.98 in) long containing dark brown seeds.

[8] Patersonia maxwellii grows in heath and seasonally wet places in near-coastal areas between Albany and Israelite Bay and on the southern Darling Range in the Jarrah Forest and Esperance Plains biogeographic regions in southern Western Australia.

[2][3] This patersonia is listed as "not threatened" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions.