Little is known about Hamilton's childhood. He was born in Oklahoma and raised in Dallas, Texas, where he received his minor public education. He met Clyde Barrow who lived in the same neighborhood as Hamilton when both men were youths, and later he would join the "Barrow Gang". Hamilton participated in the killing of Deputy Sheriff Eugene C. Moore when Moore and Sheriff Charlie Maxwell became suspicious of the men at an outdoor country dance in Stringtown, Oklahoma. Sheriff Maxwell also sustained six gunshot wounds in the exchange, but survived. It was Barrow's and Hamilton's first murder of a police officer.
Hamilton's presence in the group was often problematic, with Clyde Barrow and other members of the gang commonly referring to his girlfriend Mary O'Dare as "the washerwoman." When Hamilton was imprisoned at the Eastham prison farm north of Huntsville, Texas, Bonnie and Clyde raided the farm to free him and four other prisoners on January 16, 1934. One of the other escapees, Joe Palmer, killed a guard and caused a series of events which led to Texas Prison System chief Lee Simmons to issue a shoot to kill order against Clyde Barrow and Bonnie Parker. Simmons hired Texas RangerFrank Hamer, who formed a six-man posse in order to execute this order. Hamilton left the Barrow Gang after a fight about O'Dare and was recaptured on April 25, 1934. He was in prison when Clyde Barrow and Bonnie Parker were ambushed and killed by Hamer's posse on May 23, 1934.
Hamilton was executed on May 10, 1935 at the Texas State Penitentiary, Huntsville, Texas, by electric chair. Hamilton walked calmly and firmly to the chair and seated himself with the words "Well, goodbye all." He was preceded to the electric chair by Joe Palmer.
Raymond Hamilton never publicly admitted killing anyone, although to his brother, Floyd, he admitted that in the case of the killing of Undersheriff Eugene Moore (August 5, 1932, Stringtown, Oklahoma) he was not so sure. "Clyde and I were both shooting," Raymond told Floyd. "It could have been either one of us. Or both." Raymond Hamilton was convicted of the murder of John Bucher of Hillsboro May 1, 1932, though he had nothing to do with it. The actual killer was Ted Rogers. Clyde Barrow and Johnny Russell (not to be confused with "Uncle Bud" Russell) were accomplices.