Elachista nielsencommelinae is a moth of the Elachistidae family. It is found along the northern coast and in the subcoastal areas of the Northern Territory. The wingspan is 5–5.6 millimetres (0.20–0.22 in) for males and 5.2–6.2 millimetres (0.20–0.24 in) for females. The forewings are black with a bronzy sheen. The hindwings are dark grey. The larvae feed on Commelina species. They mine the leaves of their host plant.