Bangladesh, Cambodia, China (mainland), Japan, Laos, Mongolia (B), Myanmar, Nepal, North Korea (B), Russia (Asian), Russia (Central Asian) (B), South Korea, Thailand, Vietnam.
Vagrant to Afghanistan, Belgium, Denmark, Finland, France, Germany, Hong Kong (China), Ireland, Israel, Italy, Kazakhstan, Malaysia, Malta, Netherlands Antilles, Norway, Philippines, Poland, Spain, Sweden, United Arab Emirates, United Kingdom.
Breeds south-central and south-eastern Siberia (Novosibirsk and Russian Altai east to Stanovoy Mts, Ussuriland, Amurland and Sakhalin I), south to northern Mongolia, north-eastern China (Greater and Lesser Hinggan Mts) and northern Korea. Non-breeding northern and central Thailand, eastern Myanmar (northern Tenasserim) east to Indochina, occasionally south-eastern China (Guangdong).
 
Population
Estimated population is unknown (2010).
Radde's Warbler (Phylloscopus schwarzi) [XC284346]
by Louis A. Hansen from Comacchio (near Lido di Spina), Provincia di Ferrara, Emilia-Romagna, Italy (call)
Radde's Warbler (Phylloscopus schwarzi) [XC391593]
by from Borough Farm, Maypole, Isles of Scilly, England, United Kingdom (call)
Subspecies
No subspecies.
Has been thought to merit placement in a separate genus, Herbivocula, on basis of heavy bill, rictal bristles and large feet.