James W. Johnston (29 August 1792 – 21 November 1873) was a Nova Scotia lawyer and politician. He served as Premier of the colony from 1857 to 1860 and again from 1864. He was also Government Leader prior to the granting of responsible government in 1848. He was a Conservative and supporter of Confederation. Johnston was a descendant of Loyalists who fled the United States during the revolutionary war. Johnston was a member of the Tory establishment in Nova Scotia. In 1837 he was appointed to the Legislative Council and while he sometimes supported reform, he was generally a critic and opponent of responsible government and the introduction of party government.