The aberrant bush warbler (Horornis flavolivaceus) is a species in the bush warbler family, Cettiidae. It was formerly included in the "Old World warbler" assemblage.
It is found in central and southern China, and the northern extremes of Myanmar and Vietnam. It occurs in the countries of Bhutan, China, India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Philippines, Thailand, Timor-Leste and Vietnam and also may occur in northeastern and southeastern Bangladesh.