He was born in Aberdeen, Scotland, the son of Helen Booth and her husband, Alexander Watson.
In his youth, the family emigrated to Canada where they settled in the city of Toronto, Ontario where Alexander Watson became involved in Thoroughbred racing.
Alexander's sister, Georgina, married Ross Robertson, and they too emigrated to the United States.
In 1937, amidst rumours of race-fixing, Bobby Watson was one several jockeys whose licence was revoked by the Canadian Racing Association for what was deemed to be "suspicious behaviour."
Watson won a total of nine of the Classic races that would later form the official Canadian Triple Crown series including all three in 1945 aboard Uttermost.