Connally was born in Floresville, Texas, and graduated from the University of Texas School of Law. He served in the United States Navy during World War II.
In 1961, President John F. Kennedy named Connally secretary of the Navy. Connally resigned after 11 months to seek the Texas governorship. He was elected Governor of Texas in November, 1962 as a Democrat. He served as governor from 1963 to 1969. On November 22, 1963, he was seriously wounded while riding in President Kennedy's car in Dallas, Texas when the president was assassinated.
President Richard Nixon appointed Connally as United States Secretary of the Treasury in 1971, he served as secretary until 1972. In 1973, Connally joined the Republican party. He was an unsuccessful candidate for the Republican nomination for the 1980 U.S. presidential election