O'Brian moved with his parents to Lancaster, Pennsylvania, around 1930, when he was about five years old. His father had become an executive with the Armstrong Cork Company, which was headquartered in Lancaster. The Krampe family lived at the Stevens House Hotel temporarily before moving to the newly developed School Lane Hills houses in the city's West End. O'Brian attended Lancaster city elementary schools. The Krampes resided in Lancaster for about four years before they moved to Chicago, where his father had another position with the Armstrong Cork Company. Years later, in 1963, Hugh O'Brian was awarded the key to the city by Lancaster Mayor George Coe.