Algeria, Austria (B), Azerbaijan, Belarus (B), Bosnia and Herzegovina (B), Bulgaria (B), Croatia (Local Name: Hrvatska) (B), Czech Republic (B), Denmark (B) (P), Egypt, Estonia (B), Ethiopia, Finland (B), Germany (B), Greece (P), Hungary (B), Iran [Islamic Republic of], Iraq (P), Israel, Jordan (P), Kazakhstan (B), Kenya, Latvia (B), Libyan Arab Jamahiriya, Lithuania (B), Malawi, Moldova [Republic of] (B), Montenegro (B), Morocco, Poland (B), Romania (B), Russia (Central Asian) (B), Russia (European) (B), Saudi Arabia, Serbia (B), Slovakia (Slovak Republic) (B), Slovenia (B), South Africa, Sudan, Sweden (B), Tanzania [United Republic of], Tunisia, Turkey, Ukraine (B), Zambia, Zimbabwe.
Vagrant to Bahrain, Belgium, Botswana, Cyprus, France, Kuwait, Lebanon, Malta, Mozambique, Namibia, Netherlands Antilles, Norway, Oman, Portugal, Somalia, Spain, Svalbard and Jan Mayen Islands, Switzerland, Syrian Arab Republic, Uganda, United Arab Emirates, United Kingdom.
Breeds central and eastern Europe (eastern from southern Finland, southern Sweden, western Germany, eastern Austria and Bulgaria) east to south-western Siberia (R Irtysh region) and north-western Kazakhstan. Non-breeding eastern and southern Africa.
 
Population
Estimated population is 5,000,000 - 20,000,000 (2010).
River Warbler (Locustella fluviatilis) [XC864245]
by Lars Mogensen from Tjele, Viborg Municipality, Central Denmark Region, Denmark (song)
River Warbler (Locustella fluviatilis) [XC859051]
by Andr\u00e1s Schmidt from Fussing\u00f8 off-lead dog park (near Randers), Randers Municipality, Central Denmark Region, Hungary (song)
Subspecies
No subspecies.
Forms a species pair with Savi's Warbler (Locustella luscinioides). DNA studies indicate that the two form a group with Lanceolated Warbler (Locustella lanceolata) and Common Grasshopper-Warbler (Locustella naevia). Close affinities of these with certain Asian Bradypterus species is also suggested.