John Garibaldi Sargent was born in Ludlow, Vermont, on October 13, 1860. He earned a B.A. degree from Tufts College in 1887, and an M.A. in 1912. He studied law in the interim and was admitted to the Vermont bar in 1890. Sargent joined the firm of Stickney, Sargent & Skeels then served as State's attorney in Windsor County, Vermont, until 1900.
He served as secretary for civil and military affairs of Vermont from 1900 to 1902, and as attorney general of Vermont from 1908 to 1912. President Coolidge appointed Sargent Attorney General of the United States on March 17, 1925, and he remained in that office until March 5, 1929. Sargent was also chairman of the Vermont Commission on Uniform State Laws, and a trustee of the Black River Academy. He died on March 5, 1939, in Ludlow, Vermont.