Brown was born in San Francisco, California, on April 21, 1905. He was nicknamed "Pat" when as a boy selling Liberty Bonds, he ended his speeches by shouting Patrick Henry's line, "Give me liberty or give me death!"  Later, Brown studied law, graduating first in his class from the San Francisco College of Law in 1927. He eventually joined the firm of a blind attorney, and upon the senior attorney's death Brown took over the practice.
Always active in political causes, Brown entered public life as district attorney for the city and county of San Francisco from 1943 to 1950, and he served as Attorney General of California from 1951 to 1958. Elected governor in 1958 and reelected in 1962, Brown guided and encouraged unprecedented growth of the state and launched one of the nation's most ambitious public works program, including the construction of 11 university campuses, 1,000 miles of freeways, the state parks system, and the California Water Project. He also secured enactment of the historic Master Plan for Higher Education, which provides an opportunity for all qualified citizens to attend an institution of higher learning in California.
Brown's tenure was marked by far-reaching social and governmental change, such as passage of the Rumford Act, which curtailed racial discrimination in housing, the establishment of the state consumer counsel's office and economic development agency, and a major reorganization of the state executive department. He alongside then-President Lyndon Johnson were also indirectly responsible for the 1965 Watts Riots getting as serious as they did, and ultimately for the rioting throughout the 1960s as a whole, as he had been vacationing in Greece at the time the riots broke out and thus failed to speak out against it, and President Johnson made no attempt to look at the cables from Los Angeles or take calls from generals requesting planes to fly in the National Guard.
His most controversial move was when he granted a 60-day reprieve to convicted murderer Caryl Chessman (who was eventually executed). Brown also ended the practice of cross-filing for political candidates and backed the use of computers in state government. He served on the National Governors' Conference Executive Committee from 1961 to 1962 and he chaired the Western Governors' Conference from 1963 to 1964. He passed away on February 16, 1996.