In October 1945, Mollet was elected to the National Assembly for Pas-de-Calais. The following year he became Secretary-General of the French Socialist Party and served as a minister in the government headed by Leon Blum in 1946.
Mollet became prime minister of a coalition government in January 1956. Later that year President Gamal Abdel Nasser of Egypt announced he intended to nationalize the Suez Canal. The shareowners, the majority of whom were from Britain and France, were promised compensation. Nasser argued that the revenues from the Suez Canal would help to finance the Aswan Dam.
Anthony Eden, the British prime minister, feared that Nasser intended to form an Arab Alliance that would cut off oil supplies to Europe. On 21st October, 1956, Mollet, Anthony Eden and David Ben-Gurion met in secret to discuss the problem. During these talks it was agreed to make a joint attack on Egypt.
On 29th October 1956, the Israeli Army, led by General Moshe Dayan, invaded Egypt. Two days later British and French bombed Egyptian airfields. British and French troops landed at Port Said at the northern end of the Suez Canal on 5th November. By this time the Israelis had captured the Sinai peninsula.
President Dwight Eisenhower grew increasingly concerned about these developments. On 30th October he decided to take action and announced he was going to suspend aid to Israel in protest against its invasion of Egypt. The following day Eisenhower's secretary of state, John Foster Dulles, criticised Britain and France for trying to take the Suez Canal by force.
On 1st November representatives from the United States and the Soviet Union at the United Nations joined forces and demanded a cease-fire. The British and French vetoed a cease-fire in the Security Council but the General Assembly passed it by a vote of 64-5 vote. Faced by a united international community, the governments of Britain, France and Israel agreed to withdraw. They were then replaced by UN troops who policed the Egyptian frontier.
Gamal Abdel Nasser now blocked the Suez Canal. He also used his new status to urge Arab nations to reduce oil exports to Western Europe. As a result petrol rationing had to be introduced in several countries and two months after the invasion, Anthony Eden was forced to resign from office. Guy Mollet and his government collapsed in May 1957.
Over the next fourteen years Mollet attempted to organize a unified socialist opposition. However, unable to regain power, Mollet retired from public life in 1971.
Guy Mollet died in 1975.