Born in Hedon, England, he was brought to Canada by his father, who was a doctor, when he was one year old. He was educated in French at St. Hyacinthe in Quebec and in grammar school in Kingston, Ontario. Campbell studied law and was called to the bar in 1843. He became a partner in John A. Macdonald's law office.
He was elected to the Legislative Council in 1858 and 1864, attended the Quebec City Conference in 1864, and at Confederation was appointed to the Canadian Senate. He later held a number of ministerial posts in the Cabinet of Sir John A. Macdonald and was Lieutenant Governor of Ontario from 1887 to 1892.
He died in office in Toronto in 1892.