Byrns was born in
Cedar Hill,
Robertson County, Tennessee, son of James Henry Byrns and Mary Emily Jackson. He was named for a maternal uncle, Joseph William Green Jackson, who died in the
American Civil War. His great-grandfather, James Byrns, Esq., figures in the legend of
The Bell Witch, and is mentioned in the Authenticated History of The Bell Witch by Martin Van Buren Ingram. The Byrns family moved to
Nashville in 1885 to pursue greater educational opportunities for their children. Jo Byrns attended
Fogg High School, graduating in 1887. He then enrolled at
Vanderbilt University, where he won honors in English and history, actively participated in debates, and became a member of
Beta Theta Pi fraternity. He graduated with a law degree in 1890 and soon began building up a successful law practice. == Political career ==