Royall was born on July 24, 1894, in Goldsboro, North Carolina, the son of Clara Howard Jones and George Pender Royall. He graduated from the University of North Carolina at Chapel Hill, where he was a member of the Delta Kappa Epsilon fraternity, and Harvard Law School before serving in World War I. He then practiced law and was elected to the North Carolina Senate as a Democrat. At the beginning of World War II, he became a colonel in the US Army.