White was born in Scotland, the son of John White, a physician practicing in Paisley, Renfrewshire. He studied medicine at the University of Edinburgh, and later served as a surgeon with the rank of captain in the Royal Navy of the Kingdom of Great Britain. He relocated to the Thirteen Colonies between 1720 and 1730, first to Delaware, then Pennsylvania, and finally as a pioneer settler in present-day Frederick County, Virginia between 1732 and 1735. White was one of two physicians practicing in Frederick County, and conducted his practice from his residence near Great North Mountain. White was part of a larger wave of Scottish physicians who settled in Virginia prior to the American Revolutionary War.