Drosera coomallo is a pygmy sundew with orange flowers. It is named after the Coomallo region where it is common.

Drosera coomallo has a flat rosette of leaves that grows to around 1.7 cm in diameter. The flowers are metallic orange with black centres, reaching around 1.5 cm in diameter. The stigmas are whiplike in that they are long, thin and tapering. The filaments that support the anthers are white. The flower stalks are covered with a dense covering of glands.

The species grows in the laterite hills north of Perth where it grows in laterite atop the upper slopes of the hills. It shares this habitat with Drosera barbigera.

Drosera coomallo is distinguished from other orange-flowered pygmy sundews in the first instance by its whiplike stigmas. This trait is shared with D. albonotata, D. barbigera, D. bindoon and D. miniata. It is most similar to D. miniata in that the filaments are white (the filaments of the other species are black). Drosera coomallo differs from D. miniata in that its flower stalk is covered in dense glands (that of D. miniata are sparsely covered in glands). The ranges of these two species do not overlap, with D. coomallo growing in the hills north of Perth whereas D. miniata grows east of Perth.