Sisowath Monivong (born 1875, died 1941) was the king of Cambodia from 1927 until his death in 1941.

Sisowath Monivong was the second son of King Sisowath. He was born in Phnom Penh in 1875. During this time, his uncle, King Norodom was ruling as a puppet king for the French in the then capital of Odong , who had established a colonial protectorate. In 1884, the French conquered Laos and occupied Vietnam, and Cambodia now became a direct colonial possesion. Siam was defeated in a war but not occupied. The royal family moved from Odong to the new capital of Phnom Penh, where Sisowath Monivong was residing.

In 1904, his uncle died and his father, the crown prince, became king. Immediatly, Sisowath Monivong became the crown prince of Cambodia. In 1927, his father died, and the now elderly Sisowath Monivong became king of Cambodia. Like his father and his uncle, Monivong was a puppet for the French administration, and the real power was in the hands of the French Resident General.

It was during Monivong's rule that Cambodia became open to outside communist influences. It was during his reign that Ieng Sary, Pol Pot, and other future Cambodian communist rulers were born. In 1930, the Indochinese Communist Party was founded by Vietnamese leader Ho Chi Minh, and it became very popular in Cambodia. The Cambodian communists were intent on overthrowing the French, not the monarch.

In 1940, when France falls to the Nazi German armies, the puppet French administration, the Vichy, takes power not only in France (under German rule), but also in France's overseas colonies, including Cambodia. In late 1940, a powerless Monivong notices that Japan is making inroads in Vietnam. Soon, Japan invades and occupies Cambodia in early 1941. The Japanese allow Cambodian French Vichy officials to still rule, but under Japanese protection. So the Cambodian king was a puppet for the Vichy French, who were puppets for the Japanese in Cambodia. In western Cambodia, Thailand, now an ally of the Japanese, occupies some lands. As the Japanese and Thai oppression of Cambodians becomes evendent, Sisowath Monivong retired to Kampot in late 1941, and he died there that year.

He is succeeded by his nineteen year old grandson, Norodom Sihanouk.