Lesueur National Park lies in the Geraldton Sandplains bioregion, which is characterised by scrubby heath with a high number of plants from the family Proteaceae.

Vegetation in the park is structurally complex, with patches of woodland amongst shrublands.

The park is the northern limit for Jarrah and Mountain Marri, both of which grow as mallees instead of the more usual tall tree form.

Lesueur National Park is under threat from the effects of Phytophthora dieback, a disease which kills plants and is spread through movement of infected soil or water.

[3] In the 1980s, due to appraisals of coal deposits in the area, the Mount Lesueur and Hill River areas were in controversy over proposed coal mining and power station development,[4][5][6] until the creation of the National Park in 1990.