Bachelor of Science, University of California, 1914.
He learned Morse code when young and worked briefly as a shipboard wireless operator before entering the University of California (Class of 1914). After graduation he joined the American Marconi Company and helped to install and operate its 300-kilowatt transport-Pacific radio station at Bolinas, California and its companion receiver station in Marshall, California. From 1915-1920 Pratt was a radio aide to the United States Navy, leading its radio laboratory and engineering at Mare Island Navy Yard, California.
In this role he installed radio equipment on Navy ships and maintained West Coast shore stations until 1918, when he moved to Washington, District of Columbia, to take charge of the construction and maintenance of all high-power Navy radio stations.
From 1920-1926 Pratt worked for the Federal Telegraph Company in Palo Alto, California, where he designed a system for commercial radio telegraph service. When in 1926 the United States Congress passed the Air Commerce Acting to fund radio aids to air navigation, J. Howard Dellinger of the National Bureau of Standards tapped Pratt and Harry Diamond to create a suitable radio beacon system in 1927-1928.
In 1928 Pratt became chief engineer of the Mackay Radio and Telegraph Company, subsequently acquired by the International Telephone and Telegraph Company (International Telephone And Telegraph), where he eventually became vice president and general manager. During World World War II, Pratt served as Division Chief in the Office of Scientific Research and Development and was Chairman of the Radio Technical Planning Board 1945-1949, and in 1946 was an official observer of the Bikini atomic bomb tests.
He remained with International Telephone And Telegraph until 1951 when he served from 1951-1953 as telecommunications advisor to Presidents Truman and Eisenhower.
Pratt was vice president of the American Cable and Radio Corporation from 1953-1958. Pratt joined the Institute of Radio Engineers (Institute of Radio Engineers), became an Institute of Radio Engineers Director in 1935, served as president of the Institute of Radio Engineers in 1938, and was its secretary from 1943-1965. The Institute of Electrical and Electronics Engineers Haraden Pratt Award was established in 1971 in his honor.
His papers are archived at the Bancroft Library, University of California, Berkeley.
Fellow Institute of Electrical and Electronics Engineers (secretary, board directors), Radio Club American, American Institute of Aeronautics and Astronautics (associate). Member Institute Radio Engineers Australia (honorary life), American Standards Association (board directors 1939-1942), Sigma Xi.
Married Florence Bacon, October 31, 1924.