He graduated from Louisiana State University in Baton Rouge in 1895 and Tulane University Law School in New Orleans in 1897, where his classmates included the future state Attorney General Bolivar Edwards Kemp, Junior., and the state representative East. L. Stewart of Minden in Webster Parish.
His great-uncle was the politician Walter Hampden Overton. Tulane listed Overton as a resident of Opelousas in Saint Landry Parish. Overton was admitted to the Louisiana bar in 1898.
He established a law practice with four partners in Alexandria and was the city attorney as well.
In 1918, Overton ran for the United States. Senate but was defeated by Edward J. Gay of Plaquemine in Iberville Parish. Overton became a staunch supporter of Huey Pierce Long, Junior., and served as Long"s counsel in the impeachment proceedings against the governor in 1929.
He was elected to Congress to fill the Eighth District United States. House seat vacated by the death of Representative James B. Aswell of Natchitoches. He served in the House for slightly less than one term: from May 12, 1931, to March 4, 1933.
In 1932, he ran successfully for the United States. Senate.
He defeated the incumbent Edwin South. Broussard of New Iberia for the Democratic senatorial nomination, then equivalent to election in Louisiana. Broussard charged fraud and voter irregularities. A Senate investigating committee held months of hearings beginning in February 1933.
Overton was nevertheless seated without opposition on the then first day of the congressional session, March 4.
As a senator Overton generally voted with the conservative coalition of Midwestern Republicans and Southern Democrats. Overton was reelected in 1938 and 1944, as has been traditional with incumbent Democratic senators in Louisiana.
His committee memberships included Appropriations, Manufactures, Commerce, and Irrigation and Reclamation. His chief area of interest was in flood control and river and harbor development.
Overton attempted to withdraw from reelection race in 1944.
The letter was signed by all Democrats then in the Senate. Overton"s last term was cut short by his death at National Naval Medical Center in Bethesda, Maryland. His remains were buried at Mount Olivet Cemetery in Pineville in Rapides Parish.
His house in Alexandria was added to the National Register of Historic Places in 1985.
In 1998, Overton was posthumously inducted into the Louisiana Political Museum and Hall of Fame in Winnfield.
He was a member of the Louisiana State University Board of Supervisors.