Philip Dunham Reed was born in Milwaukee, Wisconsin on November 16, 1899. He received an under-graduate degree in Electrical Engineering at the University of Wisconsin in 1921, and an LL. B. at Fordham University Law School in 1924. He worked briefly as a patent attorney, 1921 to 1922, for Pennie, Davis, Marvin and Edwards in New York City, while attending evening law school at Fordham University. He was admitted to the New York State Bar Association in 1925.

After graduation from law school, Reed began work at Van Heusen Company as a patent counselor. He prepared their collar patent case for attorney Charles Neaves.

Reed's career at General Electric began in the New York law department in 1927. In 1928 Reed was transferred to the incandescent lamp division, becoming general counsel for that department beginning in 1934. Reed was appointed assistant to president Gerard Swope on the day after his thirty-eighth birthday, November 16, 1937, and became chairman of the board in 1939 at age 40. He held that position 18 years, from 1940 to 1942, and after World War II, from 1945 to 1959. Reed also held chairmanship of International General Electric from 1945 until its merger with the parent company in 1952. From 1958 until his retirement in 1959 he served as chairman of the Finance Committee and of the General Electric Pension Trust. During Reed's tenure as chairman, General Electric sales grew from $396 million in 1939 to $4.3 billion in 1957; company jobs during that period increased from 79,000 to more than a quarter million. During that time, General Electric invested over a billion dollars in facilities expansion. Reed was primarily concerned with customer and government relations and became a spokesman for the future of the electrical industry.

Reed's expertise in law and business led to a “dollar-a-year” appointment during World War II as Senior Consultant to the Director of Priorities, Office of Production Management in January 1942. He then served as Deputy Director, Materials Division of the War Production Board, from July to December, 1942. Other General Electric executives employed during this period of economic conversion were Charles E. Wilson, President, who became Production Vice Chairman of the War Production Board beginning in 1942, and Owen D. Young, retired Chairman of the Board. Reed was re-assigned to assist Averell Harriman as the Deputy Chief of the U.S. Mission for Economic Affairs in London in 1943, becoming chief of that mission with the rank of minister in October 1943, serving until January 1945.

After leaving the U. S. Mission for Economic Affairs, Reed served as legal consultant to the U.S. delegation to the 1945 United Nations Conference on International Organization in San Francisco; this led to Reed's long affiliation with the International Chamber of Commerce (ICC). He was a member of the ICC from 1945-1975; he served as president from 1949 to 1951. Reed headed the U.S. Mission on Anglo-American Council of Productivity, a Marshall Plan agency, established in 1948. Reed was vice chairman of the Business Advisory Council of the Department of Commerce (became the Business Council in 1961) from 1951 to 1952. He was also active in the Committee for Economic Development where he served as a trustee and a member of the Research & Policy Committee from 1946 to 1975.

Reed served as a director of the Council on Foreign Relations from 1946 to 1969; he also served as a member of the Advisory Commission on Information, the U.S. Information Agency, from 1948 to 1961.

Reed joined fourteen other businessmen in helping to persuade General Dwight D. Eisenhower to run for president in 1952. During Eisenhower's presidency, Reed acted as an informal advisor and envoy. The two men maintained a political and social relationship until Eisenhower's death.

Upon his retirement from GE in 1959, Reed became a director of the Federal Reserve Bank of New York. He served from 1959 to 1965, and was Chairman of the Board from 1960 to 1965. During these years, Reed also served on the Board of Directors of American Express; Bankers Trust Company; Bigelow-Sanford, Inc.; Cowles Communication; Kraftco Corporation; Otis; Metropolitan Life Insurance; Scott Paper; Tiffany & Co.; and U. S. Financial, Inc.

Reed was active in a wide variety of educational and cultural institutions. He was a director of the Metropolitan Opera Association from 1945 to 1953, the Carnegie Endowment for International Peace, the Ford Foundation Fund for the Advancement of Education from 1951 to 1953, and in 1960 was a member of the Committee on the University and World Affairs. He served as chairman of the Executive Committee of the International Executive Service Corps from 1966 to 1974. Reed worked with the International Executive Service Corps for over twenty years. The organization was similar to the Peace Corps in its mission to bring U.S. expertise to developing countries, but it targeted retired business and industry executives for these positions.

Reed acted as an Eisenhower Exchange Fellowships trustee from 1953 to 1975, serving as Vice Chairman from 1955 to 1975, and Chairman of the Finance Committee from 1956 to 1958. Reed also served as a Trustee of the Samuel H. Kress Foundation from 1960 to 1965, and as a Trustee of the Winston Churchill Foundation of the United States from 1970 to 1975.

Reed and his wife, Mabel, lived in Rye, New York, and Antigua, West Indies. Reed kept an office in New York City until his death on March 10, 1989.