He attended U of T and London School of Economics, specializing in the study of money. In 1930 he joined the Economic and Financial Section of the League of Nations in Geneva, Switz, and by 1939 had established a high reputation. In 1940 he became a member of the Foreign Exchange Control Board, Ottawa, organizing its research and statistics section, and by 1942 he was alternate chairman.
Much of his time was devoted to producing a "Canadian plan" for an international monetary system. In meetings before and during the conference at Bretton Woods, NH, in 1944, Rasminsky's plan was thoroughly studied and partially accepted. After WWII Rasminsky rose through the Bank of Canada hierarchy to become governor in 1961. He headed the bank for 11 years, carefully shepherding Monetary Policy through difficult times. He was chairman of the board of governors of the International Development Research Inst 1973-78. Rasminsky was named a Companion of the Order of Canada in 1968.