Hyposmocoma nihoa is a species of moth of the Cosmopterigidae family. It is endemic to Nihoa. The type locality is Miller Canyon. The wingspan is 6.3–7.6 mm. The larval case is burrito-shaped and 3.4–4.8 mm in length. It is large and rounded with a curved pointed distal end and decorated with lichens woven with silk filaments. The case background color ranges from green to gray. Adults were reared from case-making larvae. Larvae were collected on small bushes and rocks.