The Empire of Vietnam was a short-lived puppet state of Imperial Japan governing the former French protectorates of Annam and Tonkin between March 11 and August 25, 1945. At the end of its rule, the empire also successfully reclaimed Cochinchina as part of Vietnam.

Annam, or Trung Kỳ (中圻), was a French protectorate encompassing the territory of the Empire of Đại Nam in Central Vietnam. Before the protectorate's establishment, the name Annam was used in the West to refer to Vietnam as a whole; Vietnamese people were referred to as Annamites. The protectorate of Annam became a part of French Indochina in 1887, along with two other Vietnamese regions, Cochinchina in the South and Tonkin in the North. The region had a dual system of French and Vietnamese administration. The government of the Nguyễn Dynasty still nominally ruled Annam and Tonkin as the Empire of Đại Nam, with the emperor residing in Huế. In 1948, the protectorate was merged in the Provisional Central Government of Vietnam, which was replaced the next year by the newly established State of Vietnam. The French legally maintained the protectorate until they formally signed over sovereignty to the Bảo Đại and the government of the State of Vietnam in 1950 after signing the Élysée Accords in 1949. The region was divided between communist North Vietnam and anti-communist South Vietnam under the terms of the Geneva Accord of 1954.