Pierre Viénot (5 August 1897 - 20 July 1944) was a French politician and a member of the French Resistance during World War II.

Pierre Louis Gustave Viénot was born in Clermont, Oise. He studied at Lycée Janson-de-Sailly in Paris before enlisting in the French Army during World War I before his eighteenth birthday. He was wounded twice, in the Battle of the Somme (1916) and at Villers-Cotterêts (1918).

After the war, he pursued law studies and worked for Hubert Lyautey, Resident-General of French Morocco. He was influenced by Lyautey's liberal attitudes toward Moroccan governance and later promoted Franco-German relations by founding the Franco-German Committee for Information and Documentation.^[1] He married Andrée Viénot, daughter of Luxembourg businessman and patron of the Franco-German committee Émile Mayrisch, in 1929.

Viénot was elected as a deputy in 1932 representing Rocroi, Ardennes, with the French Socialist Party (PSF). He was re-elected in 1936 and served as Under-Secretary of State for Foreign Affairs in the Léon Blum government. He negotiated independence treaties for Lebanon and Syria in 1936, though these were not ratified due to opposition in the French Senate.

In 1938, he opposed the Munich Agreement and co-founded the socialist group "Agir" alongside Pierre Brossolette and Daniel Mayer, advocating resistance against Nazi Germany.

In 1940, Viénot fled France aboard the Massilia but was arrested and placed under surveillance by the Vichy government. Released in 1941, he founded the Socialist Action Committee (CAS) and later joined the French Resistance. He was arrested and detained in 1942 but managed to escape and flee to London.

There, he was appointed ambassador of Free France to the United Kingdom in 1943. He played a key role in ensuring that France would not be governed under Allied Military Government for Occupied Territories (AMGOT) after its liberation but rather by the Provisional Government of the French Republic.

Viénot died of a heart attack in London on 20 July 1944.

His wife, Andrée Viénot, later became a government minister and deputy mayor of Rocroi. Pierre Viénot is buried in Chooz, Ardennes.

• Chevalier of the Legion of Honour (for World War I service)
• Companion of the Liberation (posthumous, 23 October 1944)
• Croix de Guerre 1914-1918 (two citations)
• Medal for the War Wounded (two wounds)