Following his graduation from Chicago, Davis spent two years as a lieutenant with the U.S. Army. In 1969, he joined the Ford Motor Company as a systems analyst. He then spent five years working in corporate finance at Xerox Corporation.

In 1978, Davis became vice president of finance/public affairs for Wisconsin Power & Light Co. He was named WPL Holdings, Inc.'s president and CEO in 1990.

Davis has served as a director of Amoco Corporation and Competitive Wisconsin, Inc. and a trustee for Carnegie-Mellon University. He has been a member of University of Wisconsin System Board of Regents, the Chicago Booth Black Alumni Association, the governor's Council on Economic Issues, the Wisconsin Policy Research Institute, the Wisconsin Utilities Association, and the American Association of Blacks in Energy.