In 1938 he returned from New York to Stanford, where he earned the degree of electrical engineer, and in 1939 he and William Hewlett established their firm in Packard's garage with a capital of $538. The company, were Packard proved to be an expert administrator and Hewlett provided many technical innovations, grew into the world's largest producer of electronic testing and measurement devices. It also became a major producer of calculators, computers, and laser and ink jet printers.
Packard served as Hewlett-Packard's president from 1947 to 1964, chief executive officer from 1964 to 1968, and chairman of the board from 1964 to 1968 and from 1972 to 1993.
In 1968 President Richard M. Nixon appointed Packard deputy to Secretary of Defense Melvin Laird. Packard served until 1971, when he resigned and returned to Hewlett-Packard the next year as chairman of the board. In the 1970s and 1980s Packard was a prominent advisor to the White House on defense procurement and management.