Samuel Hume Blake was born on August 31, 1835, in Toronto, Ontario, the son of William Hume Blake, an Irish-Canadian jurist, and politician, and the brother of Edward Blake, the second Premier of Ontario.

He was a lawyer, judge, social reformer, philanthropist, and pamphleteer. He studied at the Upper Canada College and in 1850, he began a four-year apprenticeship as a clerk at the Toronto mercantile firm of Ross, Mitchell and Company. Then he decided to follow his father and older brother Edward into the legal profession, studying at the University of Toronto, graduating in 1858. After being admitted to the Law Society of Upper Canada, he entered a partnership with his older brother, thereafter, the firm was known as Blake & Blake and today it is known as Blake, Cassels & Graydon LLP. In 1872, Prime Minister Sir John A. Macdonald appointed Blake junior vice-chancellor on the Ontario Court of Chancery. In 1875, he became senior vice-chancellor. In 1881, he resigned from the bench and returned to the practice of law, representing the Canadian Pacific Railway, the Canadian Bank of Commerce, the City of Toronto government, and the University of Toronto.

In 1859, he married Rebecca M. Cronyn. He died on June 23, 1914, in Toronto, Ontario.