John R. Opel earned his MBA from Chicago Booth in 1949 and joined International Business Machines as a sales representative in Jefferson City, Missouri. He held various management posts through the 1950s, and in 1964 he became marketing vice president of the Data Processing Division, the main sales arm of IBM. He was elected a corporate vice president in 1966, appointed to the management committee in 1967, promoted to vice president of corporate finance and planning in 1968, and promoted to senior vice president in 1969. In 1974, Opel was elected president of IBM. On January 1, 1981, he became IBM's CEO and chairman of the management committee.
Opel served as a trustee for Westminster College, the Institute for Advanced Study, the Economic Club of New York, and the Joint Council on Economic Education. He was a director of the Bank of New York, the Bank of New York Co., Inc., and Pfizer, Inc. He also served on the board of governors of United Way of America and was a member of the Council of the Woodrow Wilson International Center for Scholars.