China (mainland), India, Laos, Myanmar, Thailand, Vietnam.
Breeds central, southern and south-eastern China (south-eastern Qinghai east to southern Shaanxi, Jiangxi and Fujian, south to northern and eastern Yunnan, southern Guangxi and northern and eastern Guangdong) and northern Vietnam (western Tonkin). Non-breeding southern China (southern Yunnan east to Fujian), northern and eastern Myanmar, north-western Thailand, northern Laos and northern Vietnam (eastern Tonkin).
 
Population
Estimated population is unknown (2010).
Buff-throated Warbler (Phylloscopus subaffinis) [XC883939]
by Bo Shunqi from Yita Park, Dali, Yunnan, China (call, song)
Buff-throated Warbler (Phylloscopus subaffinis) [XC187020]
by Frank Lambert from Emei Feng, Fujian, China (song)
Subspecies
No subspecies.
Has often been treated as conspecific with Tickell's Leaf-Warbler (Phylloscopus affinis), but recent studies have revealed constant vocal differences (and differences in responses to songs) between the two. The form "arcanus", based on three specimens from western Nepal (in Jan and Apr), described as a subspecies of present species, is now considered instead to be a synonym of Aberrant Bush-Warbler (Horornis flavolivaceus).