The Odessa Soviet Republic was a short-lived Soviet republic formed on January 31 1918 from parts of the Kherson and Bessarabia Governorates of the former Russian Empire.

The republic was proclaimed during the Bolshevik invasion of Ukraine immediately before Bolshevik forces pushed the Ukrainian government out of Kiev and Sfatul Ţării 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 did manage to stop the advancing Romanian Armed Forces at the Dniester and conduct a series of counter-attacks. However, the Republic ceased to exist when it was sacked by German and Austro-Hungarian troops on March 13, 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.