| Native Name: | Одесская Советская Республика (Russian) Одеська Радянська Республіка (Ukrainian) |
| Conventional Long Name: | Odessa Soviet Republic |
| Common Name: | Odessa |
| Status: | puppet state |
| Empire: | Soviet Russia |
| Life Span: | January–March 1918 |
| P1: | Ukrainian People's Republic |
| Flag P1: | Flag of Ukrainian People's Republic 1917.svg |
| P2: | Rumcherod |
| Flag P2: | Flag of Russia.svg |
| S1: | Ukrainian People's Republic |
| Flag S1: | Flag of Ukrainian People's Republic 1917.svg |
| S2: | Ukrainian Soviet Republic |
| Flag S2: | socialist_red_flag.svg |
| Flag Caption: | Flag |
| Image Map Caption: | Area claimed by the Odessa Soviet Republic in March 1918 (in green) |
| Capital: | Odessa |
| Government Type: | Soviet republic |
| Title Leader: | Chairman |
| Year Leader1: | 1918 |
| Legislature: | Council of the People's Commissars |
| Era: | World War I |
| Event Start: | Republic proclaimed |
| Date Start: | 17 January |
| Year Start: | 1918 |
| Date End: | 13 March |
| Year End: | 1918 |
| Currency: | Odessa ruble |
| Today: | Ukraine Moldova |
The Odessa Soviet Republic (OSR; Ukrainian: Одеська Радянська Республіка|translit=Odeska Radianska Respublika; Russian: Одесская Советская Республика) was a short-lived Soviet republic formed on from parts of the Kherson and Bessarabia Governorates of the former Russian Empire.
See also: Odessa Bolshevik uprising. The republic was proclaimed during the Bolshevik invasion of Ukraine immediately before Bolshevik forces pushed the Ukrainian government out of Kiev and Sfatul Țării proclaimed the independence of the Moldavian Democratic Republic. The Odessa Soviet's governing body was the Rumcherod, formed in May 1917 shortly after the February Revolution. After its Second Congress, the OSR's Soviet was chaired by Vladimir Yudovsky. He had been installed after a pro-Bolshevik coup d'état organized by the Narkom Nikolai Krylenko.
In January 1918, Yudovsky was appointed Chairman of the local Council of the People's Commissars and formed a government that included Bolsheviks, anarchists and members of the Socialist-Revolutionary Party. The government proclaimed Odessa a free city and pledged allegiance to the Bolshevik government in Petrograd. The following month, the government was liquidated by Mikhail Muravyov and merged with the regional Central Executive Committee Rumcherod.
Political instability meant that the OSR was not recognized by any other government, including Russian Bolsheviks, during its brief existence. The Republic failed to stop the Romanian occupation of Bessarabia, a region to which it laid claim. It ceased to exist altogether when it was sacked by German and Austro-Hungarian troops on 13 March 1918, two months after its creation, following the Treaty of Brest-Litovsk between the Central Powers, Ukrainian People's Republic and Petrograd Sovnarkom. The government and army evacuated first to Nikolayev, then to Sevastopol and finally to Rostov-on-Don.