Banksia brownii occurs naturally only in two population clusters between Albany and the Stirling Range in southwest Western Australia. In the Stirling Range it occurs among heath on rocky mountain slopes; further south it occurs among jarrah woodland in shallow nutrient-poor sand. It is rare and endangered in its natural habitat, with all major populations currently threatened by Phytophthora cinnamomi dieback, a disease to which the species is highly susceptible. Other threats include loss of habitat, commercial exploitation and changes to the fire regime.