Guy D. Smith was born in New York City. He attended high school at Deerfield Academy in Massachusetts before earning a B.A. in History, cum laude, from Williams College in Williamstown, Massachusetts. Guy received his J.D. cum laude from Tulane University Law School in New Orleans in 2010.

Guy served as a Judge Advocate on active duty in the United States Marine Corps for ten years. During that time he worked as a Prosecutor, Defense Counsel, and Battalion Judge Advocate for 1st Battalion, 5th Marines.

He is a Major in the United States Marine Corps Reserve where he serves as the Deputy Staff Judge Advocate for 2d Marine Logistics Group aboard Camp Lejeune, North Carolina.

Guy D. Smith was admitted to the Massachusetts Bar in 2010 and to the North Carolina Bar in 2018. He is a member of the Executive Committee of the Craven County Republican Party.