See his early autobiography (tr. 1938).
Thorez, born in Noyelles-Godault, France, became a coal miner at the age of 12. He joined the French Socialist Party in 1919, but soon after, joined the Communist Party and was imprisoned several times for political activism. In 1923 he became party secretary and, in 1930, secretary general of the party, a position he held until his death. Thorez was supported by Soviet leader Joseph Stalin for PCF leadership following splits in many Communist parties in wake of his struggle with Leon Trotsky. As the official leader, he was secretly controlled and linked to the orders of the Comintern by the secretive Eugene Fried (Annie Kriegel, Stéphane Courtois, Eugène Fried: Le grand secret du PCF, Seuil, 1997).
In 1932, Thorez became the companion of Jeannette Vermeersch; they had three sons before marrying in 1947 and remained married until his death.
Thorez was elected to the Chamber of Deputies in 1932 and was reelected in 1936. In 1934, following the Comintern directive, he helped form the Popular Front, an alliance between Communists, Socialists, and radical Socialists. The front, because of strong popular support as France was reeling from the impact of the Great Depression, won the elections of 1936. With the support of the Communists under Thorez, Léon Blum became prime minister of a Popular Front government and managed to enact long-needed social legislation. Meanwhile, Thorez presided over the massive growth of the Communist Party beginning with the elections of 1936.
Following the Nazi-Soviet Non-Aggression Pact of 1939 however, the Communist Party was outlawed and many Party members were interned. Thorez himself had his nationality revoked. Shortly thereafter, Thorez was mobilized, but he deserted from the army to flee to the Soviet Union. Thorez was tried in absentia for desertion and sentenced to death.
When General Charles de Gaulle's Free French Forces liberated France in 1944, Thorez received a pardon. After liberation, Thorez led the PCF immediately after the Second World War to a non-revolutionary road to power, instructing the wartime Communist partisans to surrender their weapons, while the party became a powerful force in the postwar governments.
In November 1944, he returned to France from the Soviet Union, and in 1945 his citizenship was restored. The PCF emerged from the Second World War as the largest political party in France based on its leading role in the anti-Nazi resistance movement during the occupation of France. Thorez was again elected to the Chamber of Deputies and reelected throughout the Fourth Republic (1946–1958). Forming a popular front with the Socialist Party in the 1945 elections, he became vice premier of France from 1946 to 1947.
By 1947 a combination of the emerging Cold War between the United States and the Soviet Union and growing social conflicts in France, linked to the increasing gap between wages and prices, put the three party union (SFIO, PCF and MRP) under heavy pressure. But the crisis came about the beginnings of the colonial war in Vietnam, the communist deputies in the Assemblée nationale voting against the communist-participating government. That incident led Premier Paul Ramadier to dismiss his Communist ministers from the government, May the 7th 1947. Contrary to a very common legend, the firing of the communist ministers was not linked to U.S. pressure, as a condition for France to benefit from the coming Marshall Plan. But the parallel movements in Italy and Belgium show that Cold War political fences were being built all over Western Europe at that time. The Communists' refusal to continue support for the French colonial reconquest of Vietnam on one hand and a wage-freeze during a period of hyperinflation on the other were the immediate triggers to the dismissal of Thorez and his colleagues from the ruling coalition in May 1947.
Although the Communists under Thorez's leadership continued to enjoy a dedicated popular following, the French political system operated to isolate and marginalize them for the remainder of the regime. Following the Cominform meeting in September 1947, Thorez abandoned its cooperative attitude towards the other political forces, intending to follow the Zhdanov doctrine. He then proved to be the most Stalinist of all communist leaders in Western Europe, blocking the evolution of his party.That lack of dynamism clearly appeared after de Gaulle came to power again in 1958 upon the founding of the French Fifth Republic, the Communist Party's strength in the Chamber dropped to 10 seats, but Thorez retained his seat.
In 1950, at the height of his popularity among party members, Thorez suffered a stroke and remained in the Soviet Union for medical care until 1953. During his absence, the party was de facto controlled by his ally Jacques Duclos, who expelled Thorez's rival André Marty. Thorez resumed his duties upon returning to France. Although his health deteriorated, Thorez remained party leader, until shortly before his death in 1964 on a Black Sea cruise.
He published Fils du peuple (1937; Son of the People, 1938) and Une politique de grandeur française (1945; "Politics of French Greatness").
The city of Torez in Ukraine is named after him. The Maurice Thorez Moscow Institute of Foreign Languages (Московский институт иностранных языков имени Мориса Тореза) was named in his honor in the Soviet Union.