The Plain Gerygone occurs in Indonesia and Timor-Leste in the Lesser Sunda region. It has pale brown upperparts and white underparts and searches shrubs for invertebrates.
The head and back are pale earthy brown, with white underparts. Flight feathers have pale edges, the tail has white tips, and the original account considered the sexes alike.
It occurs in moist forest, plantations, mangroves, montane forest, and moist savanna, catching invertebrates in shrubs.
An extinction-risk assessment has not been added yet.