Born in Houston County (now Peach Co.-Fort Valley) on April 12, 1885, to former slaves Jennie Tomlin and Jeff Walden. He attended Fort Valley High and Industrial School and was the lone graduate of the class of 1902. Austin received a bachelor's degree from Atlanta University in 1907 and a law degree from the University of Michigan in 1911.
Walden began practicing law in Macon in 1912. In June 1917 he joined the army and during World War I served as a captain and assistant judge advocate. After his discharge from the Army in 1919, he moved his law practice to Atlanta, Georgia and in 1948 he founded the Gate City Bar Association. Austin litigated civil rights cases to help President John F. Kennedy appointed him as a member of the American Battle Monuments Commission in 1963, and he was a delegate to the DNC in 1964.
Also in 1964, Walden became the first black judge in Georgia since the Reconstruction. He was appointed to serve over the Atlanta Municipal Court. Walden, the “Dean" of black lawyers in Georgia, died on July 2, 1965.