Drosera prophylla is an erect tuberous species that grows in laterite hilltops in Western Australia. As its specific epithet references, it grows numerous non-carnivorous bracts (prophylls) at the base of the erect stem. The plants are usually olive green or tinged with red. The main stem is covered in small glands but otherwise glabrous. The laminae are orbicular and are irregularly alternate, sometimes randomly occurring in opposite pairs. It has a dense covering of glandular hairs on its sepals.
The species is closely related to Drosera marchantii and was previously considered a subspecies, but differs by its many prophylls and white petals.