As suggested by its name, it is endemic to Philippia heath woodland growing on Mount Karthala on the island of Grand Comore in the Comoros.

Mount Karthala is an active volcano and future eruptions pose a serious threat to the Karthala white-eye.

The bird is further threatened by human-induced habitat loss.

The bird is approximately 3 centimetres (1.2 in) long with olive upperparts and yellow-green underparts.

Its diet consists of fruits and insects.