Eudonia mawsoni is a species of moth of the family Crambidae. It is endemic to Macquarie Island. The wingspan is 21.2–26.7 mm for males and 18.6–24.8 mm for females. The larvae and pupae have been collected mostly on mosses, but a few were collected on Colobanthus species. Whether these larvae were actually feeding on plants other than mosses is not known.