Korean reunification (Korean: 남북통일; Hanja: 南北統一) is the potential unification of North Korea and South Korea into a single Korean sovereign state. The process towards reunification was started by the June 15th North–South Joint Declaration in June 2000, and was reaffirmed by the Panmunjom Declaration for Peace, Prosperity and Unification of the Korean Peninsula in April 2018, and the joint statement of U.S. President Donald Trump and North Korean Supreme Leader Kim Jong-un at the Singapore Summit in June 2018. In the Panmunjom Declaration, the two countries agreed to work towards a peaceful reunification of Korea in the future.

Prior to World War I and Japan's annexation of Korea (1910–1945), all of Korea had been unified as a single state for centuries, known previously as the Goryeo and Joseon dynasties as well as the Korean Empire, and the penultimate state, the Korean Empire. After the end of World War II in 1945 and during the beginning of the Cold War, Korea had a unified government, the People's Republic of Korea. However, this would be brief and serve as the last government, as Korea was divided into two countries along the 38th parallel (now the Korean Demilitarized Zone) in 1948. North Korea was administered by the Workers' Party of Korea in a coalition government in the years immediately following the war, with South Korea being occupied by the United States. In 1950, North Korea invaded the South after the South engaged in mass arrests of suspected North Korea sympathizers, beginning the Korean War, which ended in stalemate in 1953. Even after the end of the Korean War, reunification proved a challenge as the two countries increasingly diverged at a steady pace. However, in the late 2010s, relations between North and South Korea warmed somewhat, beginning with North Korea's participation at the 2018 Winter Olympics in Pyeongchang County, Gangwon Province, South Korea. In 2019, South Korean President Moon Jae-in proposed reunification of the Korean peninsula by 2045.