The abdication of Bảo Đại took place on 25 August 1945 and marked the end of the 143-year reign of the Nguyễn dynasty over Vietnam ending the Vietnamese monarchy. Emperor Bảo Đại abdicated in response to the August Revolution. A ceremony was held handing power over to the newly established Democratic Republic of Vietnam, which was established during the end of World War II in Asia as Vietnam had been occupied by French and later Japanese imperialists.

The Nguyễn dynasty was the last Vietnamese dynasty, which was preceded by the Nguyễn lords and ruled the unified Vietnamese state independently from 1802 to 1883 before being a French protectorate. During its existence, the empire expanded into modern-day southern Vietnam, Cambodia, and Laos through a continuation of the centuries-long Nam tiến and Siamese–Vietnamese wars. With the French conquest of Vietnam, the Nguyễn dynasty was forced to give up sovereignty over parts of southern Vietnam to France in 1862 and 1874, and after 1883 the Nguyễn dynasty only nominally ruled the French protectorates of Annam as well as Tonkin. They later cancelled treaties with France and were the Empire of Vietnam for a short time until 25 August 1945.