Bernard Baruch was born in Camden, South Carolina to Simon and Belle Baruch. He was the second of four sons. His father Simon Baruch (1840–1921) was a German immigrant of Ashkenazi Jewish ethnicity who came with his family to the United States in 1855. He studied medicine, became a doctor, and served as a surgeon on the staff of Confederate general Robert E. Lee during the American Civil War. He was a pioneer in physical therapy. His mother's Sephardic Jewish ancestors (likely from Amsterdam or London) came to New York as early as the 1690s, where they became part of the shipping business.
In the 1890s he began to play the stock market, becoming a multi-millionaire within a decade.
In 1912 Baruch turned to politics, contributed generously to Woodrow Wilson’s first presidential campaign and, from early 1915, was a leading Democratic advocate of American military and industrial preparation for war.
In March 1918, Wilson appointed him chairman of the War Industries Board, which was in charge of mobilizing America’s industrial resources for the war effort. After the armistice, Baruch was an economic adviser to President Wilson at the Paris Peace Conference and helped to frame the economic clauses of the Peace Treaty; he described his role in Making of the Reparations and Economic Sections of the Peace Treaty (1920),
After 1919, Baruch filled the role of commentator on current events and unofficial economic adviser to presidents. Throughout, he continued to be involved in Democratic party affairs and helped finance its campaigns. He was a friend and adviser to President Franklin D. Roosevelt and his wife, Eleanor.
As Hitler grew stronger, Baruch advised America to prepare in good time and was in close touch with his friend, Winston Churchill. During World War II he chaired the Rubber Survey Committee (1942) and was adviser to the war mobilization director, James Byrnes (1943). In 1944 he was a member of a committee that studied postwar adjustment problems.
He was also the author of the first official U.S. policy proposal on the control of atomic energy submitted to the United Nations on June 14, 1946; however, the proposal was never adopted. In 1946 he was appoi nted a member of the American delegation to the United Nations Atomic Energy Commission.
He took an increasing interest in the plight of the Jews during World War II, giving sums for relief of Jewish refugees and proposing that they be settled in Uganda. At first he opposed the establishment of the State of Israel, but rallied to the Zionist cause during the debate at the United Nations in 1947. In later years, however, he never actively supported it.