Stuart-Robertson began work as a book-keeper in Bourke at the age of twelve and later owned and operated a cattle station with his brother. This was sold to finance the purchase of a softgoods store in Bourke, which opened branches in Nyngan, Byrock and Cobar. The drought caused the closure of two of the stores and Stuart-Robertson moved to Cobar, carrying on the business, as well as editing the local newspaper from 1898 to 1904. It was around this time that he wrote his book, A Woman : A Tale of the Australian Life in the Early Fifties, which some have claimed to be about his father's life.
Stuart-Robertson also assisted in organising a Miners' Union and was a Labor conference delegate. His move to Sydney in 1906 saw him working as a shop assistant and founding a Shop Assistants' Union. A staunch Labor Party member, he continued these union activities throughout his life. A Member of the New South Wales Legislative Assembly representing Camperdown (1907-1920); Balmain (1920-1927); Annandale (1927- until the day he died 2nd June,1933) , he was also Chairman of Committees (1920-1922), and the Minister for Public Health (1927). Stuart-Robertson was Vice-Chariman of the Royal National Park Trust (1923-1933).