Joseph Walker Barr was born on January 17, 1918, in Vincennes, Indiana. Barr received his B.A. from DePauw University and his M.A. in economics from Harvard University. During World War II, he was the commander of a submarine chaser in the Mediterranean. When his service in the armed forces ended, he returned home to help manage the family business.

Barr was elected to the House of Representatives from Indiana in 1958. He served on the Banking and Currency Committee, where he was principally concerned with the balance of payments problem. Barr was involved in drafting legislation creating the Inter-American Bank and the International Development Association. In 1960, Barr became an assistant to the undersecretary of the treasury, Henry Fowler.

While working as Fowler's assistant, Barr concentrated on pushing Treasury Department proposals through Congress. In January 1964, Barr was appointed chairman of the Federal Deposit Insurance Corporation (FDIC). In that capacity, he had a conflict with Comptroller James J. Saxon, whom Barr accused of being too liberal in granting bank charters. When Henry H. Fowler became secretary of the treasury in April 1965, he requested that Barr be made undersecretary. Barr's main responsibility in that post was congressional relations. He was also a supporter of a truth-in-lending proposal and the college student loan program.

Barr served as secretary of the treasury for the final month of the Johnson administration. Thereafter, he became president of the American Security and Trust Company, based in Washington, D.C. Joseph Walker Barr died of a heart attack on February 23, 1996, in Playa del Carmen, Mexico.