The Crimean status referendum of 2014 was a disputed referendum concerning the status of Crimea, held on March 16, 2014 in the Autonomous Republic of Crimea and the local government of Sevastopol (both subdivisions of Ukraine). The referendum was approved and held amidst Russia's annexation of Crimea. The referendum asked local populations whether they wanted to rejoin Russia as a federal subject, or if they wanted to restore the 1992 Crimean constitution and Crimea's status as a part of Ukraine. The official result from the Autonomous Republic of Crimea was a 97 percent vote for integration of the region into the Russian Federation with an 83 percent voter turnout, and within the local government of Sevastopol there was also a 97 percent vote for integration of the region into the Russian Federation with an 89 percent voter turnout.The March 16 referendum's available choices did not include keeping the status quo of Crimea and Sevastopol as they were at the moment the referendum was held. The 1992 constitution accords greater powers to the Crimean parliament, including full sovereign powers to establish relations with other states; therefore, many Western and Ukrainian commentators argued that both provided referendum choices would result in de facto separation from Ukraine. The final date and ballot choices were set only ten days before the plebiscite was held. Before, during and after the plebiscite was proclaimed, the Crimean peninsula was host to Russian soldiers to manage and oversee public buildings and Ukrainian military installations.Following the referendum, the State Council of Crimea and Sevastopol City Council declared the independence of the Republic of Crimea from Ukraine and requested to join the Russian Federation. On the same day, Russia recognized the Republic of Crimea as a sovereign state.The referendum is not recognized by most countries, mainly due to the presence of Russian forces. Thirteen members of the United Nations Security Council voted in favor of a resolution declaring the referendum invalid, but Russia vetoed it and China abstained. A United Nations General Assembly resolution was later adopted, by a vote of 100 in favor vs. 11 against with 58 abstentions, which declared the referendum invalid and affirmed Ukraine's territorial integrity. As the plebiscite was proclaimed, the Mejlis of the Crimean Tatar People called for a boycott of the referendum.

Crimea ( (listen) kry-MEE-ə) is a peninsula in Eastern Europe. It is situated along the northern coast of the Black Sea, and has a population of 2.4 million, made up mostly of ethnic Russians with significant Ukrainian and Crimean Tatar minorities. The peninsula is almost entirely surrounded by both the Black Sea and the smaller Sea of Azov; it is located south of Kherson Oblast in Ukraine, to which it is connected by the Isthmus of Perekop, and west of Krasnodar Krai in Russia, from which it is separated by the Strait of Kerch though linked by the Crimean Bridge since 2018. The Arabat Spit is located to its northeast, a narrow strip of land that separates a system of lagoons named Sivash from the Sea of Azov. Across the Black Sea to the west lies Romania and to the south is Turkey.

Crimea (or the Tauric Peninsula, as it was called from antiquity until the early modern period) has historically been at the boundary between the classical world and the Pontic–Caspian steppe. Its southern fringe was colonised by the Greeks and then ruled by the Persians followed by the Roman Empire, the Byzantine Empire, and finally successor states including the Empire of Trebizond and Principality of Theodoro. During the entirety of this period the urban areas were Greek-speaking and eventually eastern Christian (Eastern Orthodox). During the collapse of the Byzantine state some cities fell to its creditor, the Republic of Genoa, until eventually all were absorbed by the rapidly rising Ottoman Empire. Throughout this time the interior was occupied by a changing cast of invading steppe nomads and empires, such as the Cimmerians, Scythians, Sarmatians, Crimean Goths, Alans, Bulgars, Huns, Khazars, Kipchaks, Mongols, and the Golden Horde. Crimea and adjacent territories were united in the Crimean Khanate, a sometime dependency of the Ottomans, during the 15th to 18th century, and often raided south Russia for slaves.

In 1783, Crimea was annexed by the Russian Empire as the result of the Russo-Turkish War (1768–1774). Following the Russian Revolution of 1917, Crimea became an autonomous republic within the Russian SFSR in the Soviet Union. During World War II, Crimea was downgraded to the Crimean Oblast and the entirety of one of its indigenous populations, the Crimean Tatars, were deported to Central Asia, an act that was formally recognized as a genocide by Ukraine and three other countries between 2015 and 2019. In 1954, the Soviet Union transferred Crimea to the Ukrainian SSR from the Russian SFSR. The transfer to Ukraine was made by Soviet leader Nikita Khrushchev. The year 1954 happened to mark the 300th anniversary of the Treaty of Pereyaslav, which was signed in 1654 by representatives of the Ukrainian Cossack Hetmanate and Tsar Alexis of Russia. With the collapse of the Soviet Union, Ukraine was reestablished as an independent state in 1991, and most of the peninsula was reorganized as the Autonomous Republic of Crimea, and the city of Sevastopol retained its special status within Ukraine. The 1997 Partition Treaty on the Status and Conditions of the Black Sea Fleet partitioned the former Soviet Black Sea Fleet and allowed Russia to continue basing its fleet in Crimea: both the Ukrainian Naval Forces and Russia's Black Sea Fleet were to be headquartered in Sevastopol. Ukraine extended Russia's lease of the naval facilities under the 2010 Kharkiv Pact in exchange for further discounted natural gas.

The status of Crimea is disputed. In late February 2014, following the Revolution of Dignity that ousted the Ukrainian president, Viktor Yanukovych, Russian troops were deployed to Crimea, occupying government buildings. The Republic of Crimea declared its independence from Ukraine following a disputed referendum on 16 March, deemed illegal by Ukraine and most countries, which was held on the issue of reunification with Russia; its official results showed over 90% support for reunification, but the vote was boycotted by many loyal to Ukraine. Russia formally annexed Crimea on 18 March, incorporating the Republic of Crimea and the federal city of Sevastopol as the 84th and 85th federal subjects of Russia. Despite its annexation, Crimea was considered by most countries of the world in a UN resolution of March 2014 to remain part of Ukraine.