Bevin was reared in a poor family and left school at the age of 11. After holding a series of jobs, he found regular employment on a mineral-water delivery route in Bristol. In 1905 he became the unpaid secretary of the Bristol Right to Work Committee, and in 1910 he formed a carters' branch of the Dockers' Union in that city. By the end of World War I he was functioning as the union's assistant general secretary, though the post was not formally created until May 1920. In 1921 he amalgamated several unions into the Transport and General Workers' Union, of which he was general secretary until 1940 and which became the largest trade union in the world. From 1925 he was a member of the general council of the Trades Union Congress (TUC) and in 1937 was elected its chairman. He was prominent in organizing the British general strike of May 3–12, 1926, and was also instrumental in settling it.

During the early years of the Great Depression he criticized Ramsay MacDonald's second Labour Party government (1929–31) for failing to enact radical measures to relieve unemployment, and he refused to support MacDonald's national coalition ministry (1931–35). Through the 1930s he advocated British rearmament and a firm foreign policy to counteract the growing threat of Nazi Germany and Fascist Italy. In May 1940, when Winston Churchill formed his wartime coalition government, Bevin was appointed minister of labour and national service and was included in the War Cabinet.

When Clement Attlee formed his Labour Party government on July 26, 1945, Bevin was chosen as foreign secretary. Quickly losing his optimism about the Soviet Union, he argued (autumn 1945) against recognition of new Soviet-sponsored governments in the Balkans. To facilitate the economic and defensive rebuilding of western Europe, which was then the main theatre of the Cold War, he helped establish the Brussels Treaty alliance of the United Kingdom, France, Belgium, The Netherlands, and Luxembourg (March 17, 1948) and the Organisation for European Economic Co-operation (April 16, 1948). These agreements were followed by the signing of the North Atlantic Treaty (April 4, 1949, in Washington, D.C.). His plans (1947–48) for a federal Jewish-Arab nation or other partition of Palestine collapsed in the face of the Arab-Israeli conflict. On Jan. 6, 1950, the United Kingdom offered recognition to the People's Republic of China, contrary to United States policy. Before ill health forced his resignation on his 70th birthday, March 9, 1951, Bevin initiated the Colombo Plan (effective June 30, 1951) for economic development of South and Southeast Asia. For the last five weeks of his life he was lord privy seal.