Kyes attended Culver (Indiana) Military Academy, then transferred to the Rayen School in Youngstown, Ohio, because his father disagreed with Culver's teachings about the Civil War. He graduated from Harvard University cum laude in 1928.
Kyes worked for Glenn L. Martin Company, a manufacturer of aircraft, in Cleveland, Ohio (1929 - 1930), and then for Black and Decker Manufacturing Company, which produced electric tools, in Towson, Maryland. (1930 - 1932). He next was vice-president of the Empire Plow Company in Cleveland (1932 - 1941). During the rest of the 1940's Kyes worked for Ferguson-Sherman (later Harry Ferguson, Inc. ), a manufacturer of tractors and farm implements, in Detroit, initially as an executive consultant (1940), then as executive vice-president (1941 - 1943), general manager (1941 - 1947), and finally president (1943 - 1947).
While heading Harry Ferguson, Kyes negotiated with the General Motors Corporation (GM) concerning the latter's construction of manufacturing facilities for his firm. He impressed GM president Charles E. Wilson and joined GM in 1948 as executive in charge of procurement and schedules staff. The following year he was named assistant general manager of GM's unprofitable Truck and Coach Division. Kyes reorganized the division, cut its costs, and made it profitable within a year. Kyes became GM general manager in 1950 and was elected a vice-president.
After the outbreak of the Korean War in 1950, Kyes worked closely with Wilson on the conversion of GM facilities to the production of jeeps and other war matériel. He became well acquainted with industrial mobilization policies and developed a critical attitude toward the Pentagon's estimations of military requirements and procurement of military goods. After Dwight Eisenhower was elected president in 1952, he asked Wilson to become his secretary of defense; Wilson asked Kyes to come with him to Washington as his deputy secretary of defense. Kyes agreed to do so, but only for one year. He resigned from his $85, 000-per-year position at GM to take the $20, 000-per-year post at the Pentagon. Kyes was confirmed as deputy secretary in February 1953. Pentagon officials greeted the appointments with apprehension, since Wilson and Kyes had reputations as corporate cost cutters, and the end of active hostilities in the Korean War would mean cutbacks in military spending. After meeting Kyes, one Pentagon official said, "He looks like the kind of guy who'd say, 'Lay off 40, 000 men. ' "
His job was to oversee the day-to-day operations of the Pentagon and to act as Wilson's "hatchet man" by implementing the military cutbacks determined by Wilson and President Eisenhower.
Kyes resigned from his Pentagon post in May 1954 and was succeeded by Secretary of the Navy Robert Anderson. Kyes returned to GM as a director and group vice-president in charge of the Dayton and Household Appliance groups. He was appointed vice-president of GM's Accessory Group in September 1959, and in 1970 was named an executive vice-president of the company. Kyes retired from GM on September 30, 1970. On February 1, 1971, he joined the investment firm of Lazard Frères as a general partner.
Kyes believed that the American military establishment was characterized by "unrealistic requirements, poor planning and inefficient execution waste of money, poor utilization of manpower, unnecessary drain of materials from the civilian economy, and the inefficient use of tools, equipment and facilities. "
Kyes's reputation was enhanced by his intimidating personal appearance; his tall stature and craggy features were accentuated by protruding eyeballs resulting from a thyroid condition. At parties he would introduce himself to strangers as "the ugliest man in Washington since Abe Lincoln. "
One journalist wrote that Kyes came to Washington with the attitude that "he didn't have any friends to bring in with him and didn't expect to make any while he was at the Pentagon. "
While at Harvard, Kyes met Helen Jacoby on a blind date. They were married on June 5, 1931 and had four children.